Make sure symbol version script is writeable

[Jim Blandy]

If the source tree has been made read-only, the libstdc++-v3 build
dies trying to construct src/libstdc++-symbols.ver.

libstdc++-v3/ChangeLog:
2007-05-07  Jim Blandy  <jimb@codesourcery.com>

	* libstdc++-v3/src/Makefile.am (libstdc++-symbol.ver): Make
	sure the build tree copy of libstdc++-symbol.ver is writeable.
	* libstdc++-v3/src/Makefile.in: Regenerated.

Index: libstdc++-v3/src/Makefile.am
===================================================================
--- libstdc++-v3/src/Makefile.am	(revision 124502)
+++ libstdc++-v3/src/Makefile.am	(working copy)
@@ -32,6 +32,7 @@
 libstdc++-symbols.ver:  ${glibcxx_srcdir}/$(SYMVER_FILE) \
 		$(port_specific_symbol_files)
 	cp ${glibcxx_srcdir}/$(SYMVER_FILE) ./libstdc++-symbols.ver
+	chmod +w ./libstdc++-symbol.ver
 	if test "x$(port_specific_symbol_files)" != x; then \
 	  if grep '^# Appended to version file.' \
 	       $(port_specific_symbol_files) /dev/null > /dev/null 2>&1; then \