Fix setting of DECL_CONTEXT in pushdecl (PR c/93072).

Fix setting of DECL_CONTEXT in pushdecl (PR c/93072).

Bug 93072 is a case where the C front end (a) wrongly interprets an
inline declaration at block scope as indicating that DECL_CONTEXT
should be set for an inline function and (b) this results in an ICE.
This is a regression resulting from a previous fix of mine for other
bugs involving such declarations being wrongly interpreted elsewhere
as nested function declarations.  The fix is similar to the previous
fix: use TREE_PUBLIC instead of DECL_EXTERNAL in another place as the
relevant test to determine whether to set DECL_CONTEXT.  (When a
variable reaches the code in question in pushdecl, the two are
equivalent.)

Bootstrapped with no regressions for x86_64-pc-linux-gnu.

	PR c/93072
gcc/c:
	* c-decl.c (pushdecl): Use TREE_PUBLIC, not DECL_EXTERNAL, to
	determine whether to set DECL_CONTEXT.

gcc/testsuite:
	* gcc.dg/inline-42.c, gcc.dg/inline-43.c: New tests.