gas: Pass max_bytes to TC_FRAG_INIT

gas: Pass max_bytes to TC_FRAG_INIT

ommit 3ae729d5a4f63740ed9a778960b17c2912b0bbdd
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Wed Mar 7 04:18:45 2018 -0800

    x86: Rewrite NOP generation for fill and alignment

increased MAX_MEM_FOR_RS_ALIGN_CODE to 4095 which resulted in increase
of assembler time and memory usage by 5 times for inputs with many
.p2align directives, which is typical for LTO output.  This patch passes
max_bytes to TC_FRAG_INIT so that MAX_MEM_FOR_RS_ALIGN_CODE can be set
as needed and tracked by backend it so that HANDLE_ALIGN can check the
maximum alignment for each rs_align_code frag.  Wall time to assemble
the same cc1plus.s:

before:

423.78user 0.89system 7:05.71elapsed 99%CPU

after:

102.35user 0.27system 1:42.89elapsed 99%CPU

	PR gas/24165
	* frags.c (frag_var_init): Pass max_chars to TC_FRAG_INIT as
	max_bytes.
	* config/tc-aarch64.h (TC_FRAG_INIT): Add and pass max_bytes to
	aarch64_init_frag.
	* /config/tc-arm.h (TC_FRAG_INIT): And and pass max_bytes to
	arm_init_frag.
	* config/tc-avr.h (TC_FRAG_INIT): And and ignore max_bytes.
	* config/tc-ia64.h (TC_FRAG_INIT): Likewise.
	* config/tc-mmix.h (TC_FRAG_INIT): Likewise.
	* config/tc-nds32.h (TC_FRAG_INIT): Likewise.
	* config/tc-ns32k.h (TC_FRAG_INIT): Likewise.
	* config/tc-rl78.h (TC_FRAG_INIT): Likewise.
	* config/tc-rx.h (TC_FRAG_INIT): Likewise.
	* config/tc-score.h (TC_FRAG_INIT): Likewise.
	* config/tc-tic54x.h (TC_FRAG_INIT): Likewise.
	* config/tc-tic6x.h (TC_FRAG_INIT): Likewise.
	* config/tc-xtensa.h (TC_FRAG_INIT): Likewise.
	* config/tc-i386.h (MAX_MEM_FOR_RS_ALIGN_CODE): Set to
	(alignment ? ((1 << alignment) - 1) : 1)
	(i386_tc_frag_data): Add max_bytes.
	(TC_FRAG_INIT): Add and track max_bytes.
	(HANDLE_ALIGN): Replace MAX_MEM_FOR_RS_ALIGN_CODE with
	fragP->tc_frag_data.max_bytes.
	* doc/internals.texi: Update TC_FRAG_TYPE with max_bytes.