gnu: postgresql-13: Fix building on riscv64-linux.

* gnu/packages/databases.scm (postgresql-13)[arguments]: Add phase when
buidling for riscv64-linux to apply a patch.
[native-inputs]: When building for riscv64-linux add patch and patch
file.
* gnu/packages/patches/postgresql-riscv-spinlocks.patch: New file.
* gnu/local.mk (dist_patch_DATA): Register it.

gnu/local.mk

@@ -1644,6 +1644,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/portaudio-audacity-compat.patch		\
   %D%/packages/patches/portmidi-modular-build.patch		\
   %D%/packages/patches/postgresql-disable-resolve_symlinks.patch	\
+  %D%/packages/patches/postgresql-riscv-spinlocks.patch	\
   %D%/packages/patches/procmail-ambiguous-getline-debian.patch  \
   %D%/packages/patches/procmail-CVE-2014-3618.patch		\
   %D%/packages/patches/procmail-CVE-2017-16844.patch		\

gnu/packages/databases.scm

@@ -1278,7 +1278,29 @@ (define-public postgresql-13
                                   version "/postgresql-" version ".tar.bz2"))
               (sha256
                (base32
-                "1kf0gcsrl5n25rjlvkh87aywmn28kbwvakm5c7j1qpr4j01y34za"))))))
+                "1kf0gcsrl5n25rjlvkh87aywmn28kbwvakm5c7j1qpr4j01y34za"))))
+    (arguments
+     (if (target-riscv64?)
+       `(,@(substitute-keyword-arguments (package-arguments postgresql-14)
+             ((#:phases phases)
+              #~(modify-phases #$phases
+                  (add-after 'unpack 'apply-riscv-spinlock-patch
+                    ;; The patch is applied in this custom phase and not via the
+                    ;; "origin" object above to avoid rebuilding a large number
+                    ;; of packages on other platforms.
+                    (lambda* (#:key inputs #:allow-other-keys)
+                      (let ((patch-file
+                              #$(local-file
+                                  (search-patch
+                                    "postgresql-riscv-spinlocks.patch"))))
+                        (invoke "patch" "-p1" "-i" patch-file))))))))
+       `(,@(package-arguments postgresql-14))))
+    (native-inputs
+     (if (target-riscv64?)
+       (list
+         (local-file (search-patch "postgresql-riscv-spinlocks.patch"))
+         patch)
+       '()))))
 
 (define-public postgresql-11
   (package

gnu/packages/patches/postgresql-riscv-spinlocks.patch

@@ -0,0 +1,41 @@
+https://www.postgresql.org/message-id/dea97b6d-f55f-1f6d-9109-504aa7dfa421@gentoo.org
+
+The attached patch adds native spinlock support to PostgreSQL on RISC-V 
+systems. As suspected by Richard W.M. Jones of Red Hat back in 2016, the 
+__sync_lock_test_and_set() approach applied on arm and arm64 works here 
+as well.
+
+
+Tested against PostgreSQL 13.3 on a physical rv64gc system (BeagleV 
+Starlight beta board) - builds and installs fine, all tests pass. From 
+what I can see in gcc documentation this should in theory work on rv32 
+(and possibly rv128) as well, therefore the patch as it stands covers 
+all RISC-V systems (i.e. doesn't check the value of __risc_xlen) - but I 
+haven't confirmed this experimentally.
+
+--- a/src/include/storage/s_lock.h
++++ b/src/include/storage/s_lock.h
+@@ -315,12 +315,12 @@
+ #endif	 /* __ia64__ || __ia64 */
+ 
+ /*
+- * On ARM and ARM64, we use __sync_lock_test_and_set(int *, int) if available.
++ * On ARM, ARM64 and RISC-V, we use __sync_lock_test_and_set(int *, int) if available.
+  *
+  * We use the int-width variant of the builtin because it works on more chips
+  * than other widths.
+  */
+-#if defined(__arm__) || defined(__arm) || defined(__aarch64__) || defined(__aarch64)
++#if defined(__arm__) || defined(__arm) || defined(__aarch64__) || defined(__aarch64) || defined(__riscv)
+ #ifdef HAVE_GCC__SYNC_INT32_TAS
+ #define HAS_TEST_AND_SET
+ 
+@@ -337,7 +337,7 @@
+ #define S_UNLOCK(lock) __sync_lock_release(lock)
+ 
+ #endif	 /* HAVE_GCC__SYNC_INT32_TAS */
+-#endif	 /* __arm__ || __arm || __aarch64__ || __aarch64 */
++#endif	 /* __arm__ || __arm || __aarch64__ || __aarch64 || __riscv */
+ 
+ 
+ /* S/390 and S/390x Linux (32- and 64-bit zSeries) */