[PATCH 0/1] MR9313: configure: Only run checks in WINE_(MINGW_)PACKAGE_FLAGS when CFLAGS or LIBS is non-empty.

[Brendan Shanks (＠bshanks)]

Don't run the checks unless `_CFLAGS` or `_LIBS` is non-empty (either because they were specified manually or `pkg-config` found the package).

This fixes an issue seen on macOS: PKG_CONFIG_LIBDIR and PKG_CONFIG_PATH were set empty to prevent pkg-config from using any system-installed packages, but FFmpeg was installed in /usr/local and AC_CHECK_HEADERS/LIBS succeeded despite FFMPEG_CFLAGS/LIBS being empty. configure printed "FFmpeg development files not found.", but HAVE_FFMPEG was still set. The winedmo files compiled, but failed to link because FFMPEG_LIBS was empty.
This should also speed up configure slightly, by skipping header checks for not-installed packages.

[PATCH 1/1] configure: Only run checks in WINE_(MINGW_)PACKAGE_FLAGS when CFLAGS or LIBS is non-empty.

[Brendan Shanks]

From: Brendan Shanks

---
 aclocal.m4 | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/aclocal.m4 b/aclocal.m4
index 0597c37ece2..6f5994bce17 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -113,10 +113,12 @@ if test -s conftest.err; then
      cat conftest.err >&AS_MESSAGE_LOG_FD
 fi
 rm -f conftest.err
-ac_save_CPPFLAGS=$CPPFLAGS
-CPPFLAGS="$CPPFLAGS $ac_cflags"
-$6
-CPPFLAGS=$ac_save_CPPFLAGS
+AS_IF(
+    [test "x$ac_cflags" != "x" -o "x$ac_libs" != "x"],
+    [ac_save_CPPFLAGS=$CPPFLAGS
+     CPPFLAGS="$CPPFLAGS $ac_cflags"
+     $6
+     CPPFLAGS=$ac_save_CPPFLAGS])
 AS_VAR_POPDEF([ac_libs])dnl
 AS_VAR_POPDEF([ac_cflags])])dnl

@@ -135,10 +137,12 @@ AS_VAR_IF([ac_libs],[],
       [AS_VAR_SET_IF([MINGW_PKG_CONFIG],
       [ac_libs=`$MINGW_PKG_CONFIG --libs [$2] 2>/dev/null`])])
 m4_ifval([$3],[ac_libs=[$]{ac_libs:-"$3"}])
-ac_save_CPPFLAGS=$CPPFLAGS
-CPPFLAGS="$CPPFLAGS $ac_cflags"
-$4
-CPPFLAGS=$ac_save_CPPFLAGS
+AS_IF(
+      [test "x$ac_cflags" != "x" -o "x$ac_libs" != "x"],
+      [ac_save_CPPFLAGS=$CPPFLAGS
+       CPPFLAGS="$CPPFLAGS $ac_cflags"
+       $4
+       CPPFLAGS=$ac_save_CPPFLAGS])
 AS_VAR_POPDEF([ac_libs])dnl
 AS_VAR_POPDEF([ac_cflags])])dnl