libX11-6.2.1 and pkg-config 0.23

[Pedro Izecksohn]

  In libX11-6.2.1:

  The configure piece below is wrong, (or pkg-config is buggy) because

pkg-config --cflags xproto

  prints a line-feed only and keysymdef.h exists in my system and it is in
the right place.

  I'm using pkg-config --version 0.23

#
# Find keysymdef.h
#
KEYSYMDEF=""
for flag in $XPROTO_CFLAGS; do
	echo checking arg "$flag"
	case "$KEYSYMDEF" in
	"")
		case "$flag" in
		-I*)
			dir="`echo "$flag" | sed 's/^-I//'`"
			file="$dir/X11/keysymdef.h"
			echo looking for "$file"
			if test -f "$file"; then
				KEYSYMDEF="$file"
			fi
			;;
		esac
		;;
	esac
done
case "$KEYSYMDEF" in
"")
	{ { echo "$as_me:$LINENO: error: \"Cannot find keysymdef.h\"" >&5
echo "$as_me: error: \"Cannot find keysymdef.h\"" >&2;}
   { (exit 1); exit 1; }; }
	;;
esac

  The following is /usr/lib/pkgconfig/xproto.pc

prefix=/usr
exec_prefix=${prefix}
libdir=${exec_prefix}/lib
includedir=${prefix}/include
includex11dir=${prefix}/include/X11

Name: Xproto
Description: Xproto headers
Version: 7.0.13
Cflags: -I${includedir}