PR26569, R_RISCV_RVC_JUMP results in buffer overflow

PR26569, R_RISCV_RVC_JUMP results in buffer overflow

This patch corrects "size" and "bitsize" in R_RISCV_RVC_* reloc howtos
so that elfnn-riscv.c:perform_relocation doesn't access past the end
of a section.  I've also corrected "size" in the R_RISCV_CALL* reloc
howtos since these relocs apply to two consecutive instructions.  That
caused fallout in the assembler with complaints about "fixup not
contained within frag" due to tc-riscv.c:append_insn finishing off a
frag after the auipc insn making up a "call" macro.  Which is a little
rude since the CALL reloc also relocates the following jalr.  Fixed by
changing the frag handling a little.

I've also changed R_RISCV_ALIGN and R_RISCV_TPREL_ADD marker reloc
howtos to look like R_RISCV_NONE, and corrected dst_mask for numerous
relocs, not that it matters very much.

bfd/
	PR 26569
	* elfxx-riscv.c (howto_table): Correct size and bitsize of
	R_RISCV_RVC_BRANCH, R_RISCV_RVC_JUMP, and R_RISCV_RVC_LUI.
	Correct size for R_RISCV_TLS_DTPMOD32, R_RISCV_TLS_DTPREL32,
	R_RISCV_CALL, and R_RISCV_CALL_PLT.  Make R_RISCV_TPREL_ADD and
	R_RISCV_ALIGN like R_RISCV_NONE.  Correct dst_mask many relocs.
gas/
	* config/tc-riscv.c (append_insn): Don't tie off frags at CALL
	relocs.
	(riscv_call): Tie them off after the jalr.
	(md_apply_fix): Zero fx_size of RELAX fixup.