i386: Add more peephole2 for APX NDD

i386: Add more peephole2 for APX NDD

The patch aims to optimize
         movb    (%rdi), %al
         movq    %rdi, %rbx
         xorl    %esi, %eax, %edx
         movb    %dl, (%rdi)
         cmpb    %sil, %al
	 jne
to
         xorb    %sil, (%rdi)
         movq    %rdi, %rbx
	 jne

Reduce 2 mov and 1 cmp instructions.

Due to APX NDD allowing the dest register and source register to be different,
some original peephole2 are invalid. Add new peephole2 patterns for APX NDD.

gcc/ChangeLog:

	* config/i386/i386.md (define_peephole2): Define some new peephole2 for
	APX NDD.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/pr49095-2.c: New test.