Fix compilation warning by MinGW GCC.

 setenv.c [!HAVE_ENVIRON_DECL]: Avoid declaring environ if it is
 a macro, as this causes compiler warnings with MinGW.
Avoid MinGW warnings about redefinition of snprintf.

 gdb/python/python-internal.h (HAVE_SNPRINTF)
 [_WIN32 && HAVE_DECL_SNPRINTF]: Define, to avoid compiler warnings
 about redefinition of snprintf by pyerrors.h.
gdb/testsuite/
	* gdb.base/valgrind-infcall.exp
	(continue #$continue_count) <remote connection closed>
	(continue #$continue_count) <valgrind vgdb has terminated>: Add kill of
	$valgrind_pid.
merge from gcc
daily update
*** empty log message ***
	PR ld/12549
bfd/
	* elflink.c (elf_link_add_object_symbols): Exclude weak refs when
	considering whether an --as-needed library is needed.
ld/
	* ld.texinfo (--as-needed): Update.
ld/testsuite/
	* ld-elf/pr14862.out: Expect no output.
daily update