libstdc++ testsuite regressions

[David Edelsohn]

	I am seeing new libstdc++ failures because some tests are
referencing setenv(), but the function is not declared:

/farm/dje/src/src/libstdc++-v3/testsuite/22_locale/locale/cons/5.cc: In function
 'void test04()':
/farm/dje/src/src/libstdc++-v3/testsuite/22_locale/locale/cons/5.cc:66: error: '
setenv' was not declared in this scope
/farm/dje/src/src/libstdc++-v3/testsuite/22_locale/locale/cons/5.cc:71: error: '
setenv' was not declared in this scope

	getenv() appears to be declared, but not setenv():

./c_compatibility/stdlib.h:using std::getenv;
./c_std/std_cstdlib.h:#undef getenv
./c_std/std_cstdlib.h:  using ::getenv;

David