meson: drop separate version library

When building `libgit.a` we link it against a `libgit_version.a` library
that contains the version information that we inject at build time. The
intent of this is to avoid rebuilding all of `libgit.a` whenever the
version changes. But that wouldn't happen in the first place, as we know
to just rebuild the files that depend on the generated "version-def.h"
file.

This is an artifact of an earlier version of the Meson build infra that
didn't ultimately land. We didn't yet have "version-def.h", and instead
injected the version via preprocessor directives. And here we would have
rebuilt all of `libgit.a` indeed in case the version changes, because
the preprocessor directive applied to all files.

Stop building the separate library and instead add "version-def.h" to
the list of source files directly.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

meson.build

@@ -478,6 +478,7 @@ libgit_sources = [
   'userdiff.c',
   'utf8.c',
   'varint.c',
+  'version.c',
   'versioncmp.c',
   'walker.c',
   'wildmatch.c',
@@ -1542,26 +1543,14 @@ version_def_h = custom_target(
   depends: [git_version_file],
   env: version_gen_environment,
 )
-
-# Build a separate library for "version.c" so that we do not have to rebuild
-# everything when the current Git commit changes.
-libgit_version_library = static_library('git-version',
-  sources: [
-    'version.c',
-    version_def_h,
-  ],
-  c_args: libgit_c_args + [
-    '-DGIT_VERSION_H="' + version_def_h.full_path() + '"',
-  ],
-  dependencies: libgit_dependencies,
-  include_directories: libgit_include_directories,
-)
+libgit_sources += version_def_h
 
 libgit = declare_dependency(
   link_with: static_library('git',
     sources: libgit_sources,
-    c_args: libgit_c_args,
-    link_with: libgit_version_library,
+    c_args: libgit_c_args + [
+      '-DGIT_VERSION_H="' + version_def_h.full_path() + '"',
+    ],
     dependencies: libgit_dependencies,
     include_directories: libgit_include_directories,
   ),