libpkgconf: pkg: use a second pointer for demunging windows paths

NEWS

@@ -1,6 +1,12 @@
 Changes from previous version of pkgconf
 ========================================
 
+Changes from 1.7.1 to 1.7.2:
+----------------------------
+
+* Bug fixes:
+  - Fix a windows-specific crash relating to path fixups.
+
 Changes from 1.7.0 to 1.7.1:
 ----------------------------
 

libpkgconf/pkg.c

@@ -389,8 +389,9 @@ pkgconf_pkg_new_from_file(pkgconf_client_t *client, const char *filename, FILE *
 	 * strrchr() took us to the last \ in that case, so we just have to see if
 	 * it is followed by a /.  If so, lop it off.
 	 */
-	if ((idptr = strrchr(idptr, '/')) != NULL)
-		idptr++;
+	char *mungeptr;
+	if ((mungeptr = strrchr(idptr, '/')) != NULL)
+		idptr = mungeptr++;
 #endif
 
 	pkg->id = strdup(idptr);