gnu: gcc@4.9: Fix libsanitizer compilation with glibc 2.26.

* gnu/packages/patches/gcc-4.9-libsanitizer-fix.patch: New file.
* gnu/packages/gcc.scm (gcc-4.9)[source](patches): Add it.
* gnu/local.mk (dist_patch_DATA): Add it.

gnu/local.mk

@@ -662,6 +662,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/gcc-asan-missing-include.patch		\
   %D%/packages/patches/gcc-cross-environment-variables.patch	\
   %D%/packages/patches/gcc-fix-texi2pod.patch			\
+  %D%/packages/patches/gcc-4.9-libsanitizer-fix.patch		\
   %D%/packages/patches/gcc-libsanitizer-fix.patch		\
   %D%/packages/patches/gcc-libvtv-runpath.patch			\
   %D%/packages/patches/gcc-strmov-store-file-names.patch	\

gnu/packages/gcc.scm

@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2014, 2015, 2018 Mark H Weaver <mhw@netris.org>
 ;;; Copyright © 2014, 2015, 2016, 2017 Ricardo Wurmus <rekado@elephly.net>
 ;;; Copyright © 2015 Andreas Enge <andreas@enge.fr>
@@ -392,7 +392,8 @@ (define-public gcc-4.9
               (sha256
                (base32
                 "14l06m7nvcvb0igkbip58x59w3nq6315k6jcz3wr9ch1rn9d44bc"))
-              (patches (search-patches "gcc-arm-bug-71399.patch"
+              (patches (search-patches "gcc-4.9-libsanitizer-fix.patch"
+                                       "gcc-arm-bug-71399.patch"
                                        "gcc-asan-missing-include.patch"
                                        "gcc-libvtv-runpath.patch"
                                        "gcc-fix-texi2pod.patch"))

gnu/packages/patches/gcc-4.9-libsanitizer-fix.patch

@@ -0,0 +1,66 @@
+This is a backport of this patch from 6.5 to 4.9:
+
+  https://gcc.gnu.org/git/?p=gcc.git;a=patch;h=8937b94d1a643fd9760714642296d034a45254a8
+
+diff --git a/libsanitizer/sanitizer_common/sanitizer_linux.cc b/libsanitizer/sanitizer_common/sanitizer_linux.cc
+index 69c9c10..8e53673 100644
+--- a/libsanitizer/sanitizer_common/sanitizer_linux.cc
++++ b/libsanitizer/sanitizer_common/sanitizer_linux.cc
+@@ -599,8 +599,7 @@ uptr internal_prctl(int option, uptr arg2, uptr arg3, uptr arg4, uptr arg5) {
+   return internal_syscall(__NR_prctl, option, arg2, arg3, arg4, arg5);
+ }
+ 
+-uptr internal_sigaltstack(const struct sigaltstack *ss,
+-                         struct sigaltstack *oss) {
++uptr internal_sigaltstack(const void *ss, void *oss) {
+   return internal_syscall(__NR_sigaltstack, (uptr)ss, (uptr)oss);
+ }
+ 
+diff --git a/libsanitizer/sanitizer_common/sanitizer_linux.h b/libsanitizer/sanitizer_common/sanitizer_linux.h
+index 6422df1..8a8e526 100644
+--- a/libsanitizer/sanitizer_common/sanitizer_linux.h
++++ b/libsanitizer/sanitizer_common/sanitizer_linux.h
+@@ -18,7 +18,6 @@
+ #include "sanitizer_platform_limits_posix.h"
+ 
+ struct link_map;  // Opaque type returned by dlopen().
+-struct sigaltstack;
+ 
+ namespace __sanitizer {
+ // Dirent structure for getdents(). Note that this structure is different from
+@@ -28,8 +27,7 @@ struct linux_dirent;
+ // Syscall wrappers.
+ uptr internal_getdents(fd_t fd, struct linux_dirent *dirp, unsigned int count);
+ uptr internal_prctl(int option, uptr arg2, uptr arg3, uptr arg4, uptr arg5);
+-uptr internal_sigaltstack(const struct sigaltstack* ss,
+-                          struct sigaltstack* oss);
++uptr internal_sigaltstack(const void *ss, void *oss);
+ uptr internal_sigaction(int signum, const __sanitizer_kernel_sigaction_t *act,
+     __sanitizer_kernel_sigaction_t *oldact);
+ uptr internal_sigprocmask(int how, __sanitizer_kernel_sigset_t *set,
+diff --git a/libsanitizer/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc b/libsanitizer/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc
+index 6ee63ec..50c21a3 100644
+--- a/libsanitizer/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc
++++ b/libsanitizer/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc
+@@ -238,7 +238,7 @@ static int TracerThread(void* argument) {
+ 
+   // Alternate stack for signal handling.
+   InternalScopedBuffer<char> handler_stack_memory(kHandlerStackSize);
+-  struct sigaltstack handler_stack;
++  stack_t handler_stack;
+   internal_memset(&handler_stack, 0, sizeof(handler_stack));
+   handler_stack.ss_sp = handler_stack_memory.data();
+   handler_stack.ss_size = kHandlerStackSize;
+diff --git a/libsanitizer/tsan/tsan_platform_linux.cc b/libsanitizer/tsan/tsan_platform_linux.cc
+index fe69430..49f5270 100644
+--- a/libsanitizer/tsan/tsan_platform_linux.cc
++++ b/libsanitizer/tsan/tsan_platform_linux.cc
+@@ -351,7 +351,7 @@ bool IsGlobalVar(uptr addr) {
+ // closes within glibc. The code is a pure hack.
+ int ExtractResolvFDs(void *state, int *fds, int nfd) {
+   int cnt = 0;
+-  __res_state *statp = (__res_state*)state;
++  struct __res_state *statp = (struct __res_state*)state;
+   for (int i = 0; i < MAXNS && cnt < nfd; i++) {
+     if (statp->_u._ext.nsaddrs[i] && statp->_u._ext.nssocks[i] != -1)
+       fds[cnt++] = statp->_u._ext.nssocks[i];