PR bootstrap/12490
	* scan-decls.c (MAX_EXTERN_C_BRACES): New preprocessor constant
	to define the size of the extern_C_braces array.  Set it to 200.
	(scan_decls): Abort when extern_C_braces_length is out-of-bounds.

Co-Authored-By: Eric Botcazou <ebotcazou@libertysurf.fr>

From-SVN: r72224