meson: Factor out the AC_REPLACE_FUNCS stuff to its own library

This is all just stuff we wish we had in libc, and some of this gets
used in eg. the dmx utilities build, so split it to its own library to
avoid pulling in xserver stuff.

Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Adam Jackson <ajax@redhat.com>

os/meson.build

@@ -20,26 +20,27 @@ srcs_os = [
 ]
 
 # Wrapper code for missing C library functions
+srcs_libc = []
 if not cc.has_function('reallocarray')
-    srcs_os += 'reallocarray.c'
+    srcs_libc += 'reallocarray.c'
 endif
 if not cc.has_function('strcasecmp')
-    srcs_os += 'strcasecmp.c'
+    srcs_libc += 'strcasecmp.c'
 endif
 if not cc.has_function('strcasestr')
-    srcs_os += 'strcasestr.c'
+    srcs_libc += 'strcasestr.c'
 endif
 if not cc.has_function('strlcat')
-    srcs_os += 'strlcat.c'
+    srcs_libc += 'strlcat.c'
 endif
 if not cc.has_function('strlcpy')
-    srcs_os += 'strlcpy.c'
+    srcs_libc += 'strlcpy.c'
 endif
 if not cc.has_function('strndup')
-    srcs_os += 'strndup.c'
+    srcs_libc += 'strndup.c'
 endif
 if not cc.has_function('timingsafe_memcmp')
-    srcs_os += 'timingsafe_memcmp.c'
+    srcs_libc += 'timingsafe_memcmp.c'
 endif
 
 if cc.has_function('poll')
@@ -53,6 +54,14 @@ if get_option('xdmcp')
     srcs_os += 'xdmcp.c'
 endif
 
+libxlibc = []
+if srcs_libc.length() > 0
+    libxlibc = static_library('libxlibc',
+        srcs_libc,
+        include_directories: inc,
+    )
+endif
+
 libxserver_os = static_library('libxserver_os',
     srcs_os,
     include_directories: inc,
@@ -62,4 +71,5 @@ libxserver_os = static_library('libxserver_os',
         sha1_dep,
         dependency('xau')
     ],
+    link_with: libxlibc,
 )