[FFmpeg-cvslog] configure: add pkg-config check for zlib

[Jan Ekström]

ffmpeg | branch: master | Jan Ekström <jeebjp at gmail.com> | Sat May  5 21:57:44 2018 +0300| [8d1263fa199ff6dcfc8f0cc94f15f3b429d0c276] | committer: Jan Ekström

configure: add pkg-config check for zlib

It exists, so why not use it? Helps one get rid of additional
search path related flags in addition to PKG_CONFIG_{PATH,LIBDIR}
when utilizing a cross-prefix separate from the sysroot.

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=8d1263fa199ff6dcfc8f0cc94f15f3b429d0c276
---

 configure | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/configure b/configure
index f78853cc6c..2d99c8ea85 100755
--- a/configure
+++ b/configure
@@ -5933,7 +5933,8 @@ if ! disabled pthreads && ! enabled w32threads && ! enabled os2threads; then
     fi
 fi
 
-enabled  zlib && check_lib zlib   zlib.h      zlibVersion    -lz
+enabled  zlib && { check_pkg_config zlib zlib "zlib.h" zlibVersion ||
+                   check_lib zlib   zlib.h      zlibVersion    -lz; }
 enabled bzlib && check_lib bzlib bzlib.h BZ2_bzlibVersion    -lbz2
 enabled  lzma && check_lib lzma   lzma.h lzma_version_number -llzma