re PR c/5059 (Compiling s/w containing the use of DIR.H fails on other stat-calls)

re PR c/5059 (Compiling s/w containing the use of DIR.H fails on other stat-calls)

	* config/alpha/osf.h (TARGET_OS_CPP_BUILTINS): Rename
	__EXTERN_PREFIX to __PRAGMA_EXTERN_PREFIX.
	* doc/extend.texi (Tru64 Pragmas): Reflect this.

	* fixinc/inclhack.def (alpha___extern_prefix): Indicate #pragma
	extern_prefix support for Tru64 UNIX V5 <sys/stat.h>.
	* fixinc/fixincl.x: Regenerate.
	* fixinc/tests/base/sys/stat.h [ALPHA___EXTERN_PREFIX_CHECK]: New
	testcase.
	Fixes PR c/5059, c/6126, other/9671.

	testsuite:
	* g++.dg/other/pragma-ep-1.C: Test for __PRAGMA_EXTERN_PREFIX.
	* gcc.dg/pragma-ep-1.c: Likewise.

From-SVN: r63370