LD/testsuite: Conditionalize the placement of `.dynamic' in GNU_RELRO

LD/testsuite: Conditionalize the placement of `.dynamic' in GNU_RELRO

Complement commit d345186d0535 ("Check if GNU_RELRO segment is is
generated") and exclude the presence of a `.dynamic' section from
implying the creation of a GNU_RELRO segment for targets which place the
section in the (read-only) text segment, and therefore cannot have the
section assigned to GNU_RELRO and neither it would make sense.

Currently the list of such targets consists of 64-bit HPPA and
non-VxWorks MIPS targets, as determined by looking for TEXT_DYNAMIC
being set across ld/emulparams/* and then verified by examining default
linker scripts produced in a `--enable-targets=all' build.

	ld/
	* testsuite/ld-elf/binutils.exp (binutils_test): Make the
	expectation for `.dynamic' in GNU_RELRO segment target-specific.