PR ld/15302
	* elf32-arm.c (allocate_dynrelocs_for_symbol): Transform
	ST_BRANCH_TO_ARM into ST_BRANCH_TO_THUMB if the target only
	supports thumb instructions.

	PR ld/15302
	* ld-arm/branch-lks-sym.ld: New script.
	* ld-arm/thumb-b-lks-sym.s: New test.
	* ld-arm/thumb-b-lks-sym.d: Expected disassembly.
	* ld-arm/thumb-bl-lks-sym.s: New test.
	* ld-arm/thumb-bl-lks-sym.d: Expected disassembly.
	* ld-arm/arm-elf.exp: Run the new tests.
	* posix.sgml (fcntl, flock, lockf): Point to implementation notes.