ARM CMSE symbols

ARM CMSE symbols

This patch removes use of st_target_internal to cache the result of
comparing symbol names against CMSE_PREFIX.  The problem with setting
a bit in st_target_internal in swap_symbol_in is that calling
bfd_elf_sym_name from swap_symbol_in requires symtab_hdr, and you
don't know for sure whether swap_symbol_in is operating on dynsyms
(and thus elf_tdata (abfd)->dynsymtab_hdr should be used) or on the
normal symtab (thus elf_tdata (abfd)->symtab_hdr).  You can make an
educated guess based on abfd->flags & DYNAMIC but that relies on
knowing a lot about calls to bfd_elf_get_elf_syms, and is fragile in
the face of possible future changes.

include/
	* elf/arm.h (ARM_GET_SYM_CMSE_SPCL, ARM_SET_SYM_CMSE_SPCL): Delete.
bfd/
	* elf32-arm.c (cmse_scan): Don't use ARM_GET_SYM_CMSE_SPCL,
	instead recognize CMSE_PREFIX in symbol name.
	(elf32_arm_gc_mark_extra_sections): Likewise.
	(elf32_arm_filter_cmse_symbols): Don't test ARM_GET_SYM_CMSE_SPCL.
	(elf32_arm_swap_symbol_in): Don't invoke ARM_SET_SYM_CMSE_SPCL.