build: add pkgconfig files

patch by Jan Engelhardt (jengelh at medozas dot de)

fixes http://code.google.com/p/webp/issues/detail?id=64

Change-Id: I5b3bc9b88af967e48b949d9c85daacda45693b1f

configure.ac

@@ -3,6 +3,11 @@ AM_INIT_AUTOMAKE
 AC_PROG_LIBTOOL
 AM_PROG_CC_C_O
 
+AC_ARG_WITH([pkgconfigdir], AS_HELP_STRING([--with-pkgconfigdir=PATH],
+	[Path to the pkgconfig directory [[LIBDIR/pkgconfig]]]),
+	[pkgconfigdir="$withval"], [pkgconfigdir='${libdir}/pkgconfig'])
+AC_SUBST([pkgconfigdir])
+
 dnl === check for PNG support ===
 
 PNG_INCLUDES=""

src/.gitignore

@@ -0,0 +1 @@
+/*.pc

src/Makefile.am

@@ -10,3 +10,7 @@ libwebp_la_LDFLAGS = -version-info 0:0:0
 libwebpinclude_HEADERS = webp/types.h webp/decode.h webp/decode_vp8.h \
                          webp/encode.h
 libwebpincludedir = $(includedir)/webp
+
+pkgconfig_DATA = libwebp.pc
+
+${pkgconfig_DATA}: ${top_builddir}/config.status

src/libwebp.pc.in

@@ -0,0 +1,11 @@
+prefix=@prefix@
+exec_prefix=@exec_prefix@
+libdir=@libdir@
+includedir=@includedir@
+
+Name:		libwebp
+Description:	Library for the WebP graphics format
+Version:	@PACKAGE_VERSION@
+Cflags:		-I${includedir}
+Libs:		-L${libdir} -lwebp
+Libs.private:	-lm