* doc/tm.texi.in (TARGET_ASM_MERGEABLE_RODATA_PREFIX): Add hook.
	* doc/tm.texi: Regenerate.
	* target.def (mergeable_rodata_prefix: New defhookpod.
	* varasm.c (mergeable_string_section, mergeable_constant_section):
	Use it. Allocate name with alloca.

From-SVN: r176235