Add --static to PKG_CONFIG rather than replacing it.

compat.h

@@ -190,7 +190,7 @@ typedef uint64_t u_int64_t;
 
 #ifndef HAVE_CLOSEFROM
 /* closefrom.c */
-void	closefrom(int);
+void		 closefrom(int);
 #endif
 
 #ifndef HAVE_STRCASESTR

configure.ac

@@ -48,7 +48,7 @@ AC_ARG_ENABLE(
 )
 if test "x$found_static" = xyes; then
 	LDFLAGS="$LDFLAGS -static"
-	PKG_CONFIG="pkg-config --static"
+	test "x$PKG_CONFIG" != x && PKG_CONFIG="$PKG_CONFIG --static"
 fi
 
 # Is this gcc?