Forcefully set PKG_CONFIG_PATH and PKG_CONFIG_LIBDIR for pkgconfig only if...

Forcefully set PKG_CONFIG_PATH and PKG_CONFIG_LIBDIR for pkgconfig only if these environment variables haven't been set yet. And the path /usr/lib/pkgconfig exists. This fixes building wxwidgets in contrib for Fedora Core 6

extras/contrib/bootstrap

@@ -146,8 +146,15 @@ case $HOST in
         ;;
     *)
             if test "$HOST" = "$BUILD"; then
+		if test -d "/usr/lib/pkgconfig"; then
+		    if test -z "$PKG_CONFIG_PATH"; then
+	               	echo "PKG_CONFIG_PATH = /usr/lib/pkgconfig" >> config.mak
+		    fi
+		    if test -z "$PKG_CONFIG_LIBDIR"; then
                 	echo "PKG_CONFIG_LIBDIR = /usr/lib/pkgconfig" >> config.mak
 		    fi
+		fi
+            fi
             # Try to match distribution
             if test -f /etc/fedora-release; then
                 cat src/Distributions/fedora.mak >> distro.mak