gnu: ninja: Do not report files with mtime = 0 as missing.

This is a followup to 47f315a.

* gnu/packages/patches/ninja-zero-mtime.patch: New file.
* gnu-system.am (dist_patch_DATA): Add it.
* gnu/packages/ninja.scm (ninja)[source]: Reinstate 'patches' field and add
  this patch.
  [arguments]: Remove 'apply-ninja-tests.patch' phase.

gnu-system.am

@@ -537,6 +537,7 @@ dist_patch_DATA =						\
   gnu/packages/patches/ngircd-handle-zombies.patch		\
   gnu/packages/patches/ngircd-no-dns-in-tests.patch		\
   gnu/packages/patches/ninja-tests.patch			\
+  gnu/packages/patches/ninja-zero-mtime.patch			\
   gnu/packages/patches/nss-pkgconfig.patch			\
   gnu/packages/patches/nvi-assume-preserve-path.patch		\
   gnu/packages/patches/nvi-dbpagesize-binpower.patch		\

gnu/packages/ninja.scm

@@ -23,7 +23,6 @@ (define-module (gnu packages ninja)
   #:use-module (guix download)
   #:use-module (guix build-system gnu)
   #:use-module (gnu packages)
-  #:use-module (gnu packages base)
   #:use-module (gnu packages python))
 
 (define-public ninja
@@ -38,23 +37,13 @@ (define-public ninja
               (sha256
                (base32
                 "1h3yfwcfl61v493vna6jia2fizh8rpig7qw2504cvkr6gid3p5bw"))
-              ;; XXX Ninja's build system doesn't cope well with zeroed
-              ;; time stamps in the source tree, so we must avoid using
-              ;; 'patch-and-repack'.
-              #; (patches (list (search-patch "ninja-tests.patch")))))
+              (patches (map search-patch
+                            '("ninja-zero-mtime.patch" "ninja-tests.patch")))))
     (build-system gnu-build-system)
-    (native-inputs `(("python" ,python-2)
-                     ("patch" ,patch)
-                     ("ninja-tests.patch" ,(search-patch "ninja-tests.patch"))))
+    (native-inputs `(("python" ,python-2)))
     (arguments
      '(#:phases
        (modify-phases %standard-phases
-         (add-after
-          'unpack 'apply-ninja-tests.patch
-          ;; XXX Apply the patch here to avoid 'patch-and-repack'.  See above.
-          (lambda* (#:key inputs #:allow-other-keys)
-            (zero? (system* "patch" "--force" "-p1" "-i"
-                            (assoc-ref inputs "ninja-tests.patch")))))
          (replace
           'configure
           (lambda _

gnu/packages/patches/ninja-zero-mtime.patch

@@ -0,0 +1,19 @@
+Work around a design defect in Ninja whereby a zero mtime is used to
+denote missing files (we happen to produce files that have a zero mtime
+and yet really do exist.)
+
+--- ninja-1.5.3/src/disk_interface.cc	2014-11-24 18:37:47.000000000 +0100
++++ ninja-1.5.3/src/disk_interface.cc	2015-07-18 23:20:38.572290139 +0200
+@@ -194,6 +194,12 @@ TimeStamp RealDiskInterface::Stat(const
+     }
+     return -1;
+   }
++
++  if (st.st_mtime == 0)
++    // All the code assumes that mtime == 0 means "file missing".  Here we
++    // know the file is not missing, so tweak the mtime.
++    st.st_mtime = 1;
++
+   return st.st_mtime;
+ #endif
+ }