Darwin: Place global inits in the correct section.

Darwin: Place global inits in the correct section.

This handles placement of global initializers into __TEXT,__StaticInit as used
by other platform toolchains.

Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
gcc/ChangeLog:

	* config/darwin-sections.def (static_init_section): Add the
	__TEXT,__StaticInit section.
	* config/darwin.c (darwin_function_section): Use the static init
	section for global initializers, to match other platform toolchains.

(cherry picked from commit 68dc3e94fd6bd395a8b343533485616dff3fc796)