LoongArch: Prepare static PIE support

LoongArch: Prepare static PIE support

Static PIE allows us to extend the ASLR to cover static executables and
it's not too difficult to support it.  On GCC side, we just pass a group
of options to the linker, like other ports with static PIE support.

The real implementation of static PIE (rcrt1.o) will be added into Glibc
later.

gcc/ChangeLog:

	* config/loongarch/gnu-user.h (GNU_USER_TARGET_LINK_SPEC): For
	-static-pie, pass -static -pie --no-dynamic-linker -z text to
	the linker, and do not pass --dynamic-linker.