Preliminary GAS parser. Only a few instructions are supported at present.

Preliminary GAS parser.  Only a few instructions are supported at present.
This work is being done under contract with a company that has requested
to remain unnamed at the present time.

* bc-int.h (yasm_effaddr): Add strong flag to indicate if the effective
address is definitely an effective address; GAS does not use [] to designate
effective addresses so it's otherwise impossible to tell the difference
between "expr(,1)" and just "expr" (important for the relative jump
instructions).
* bytecode.h (yasm_ea_set_strong): New function to set the strong flag.
* bytecode.c (yasm_ea_set_strong): Implementation.
* x86bc.c (yasm_x86__ea_create_reg): Initialize strong flag.

* arch.h (yasm_insn_operand): Add deref flag to indicate use of "*foo" in
GAS syntax.
* arch.c (yasm_operand_create_reg, yasm_operand_create_segreg)
(yasm_operand_create_mem, yasm_operand_create_imm): Set deref flag to 0.

* gas: GAS syntax lexer and parser.  Not all directives are implemented yet
(some will require additional core bytecodes).

* elf-objfmt.c (elf_objfmt_section_switch): Add support for GAS-style
section flags.

* x86arch.h (yasm_arch_x86): Add parser setting.
* x86arch.c (x86_create): Check for gas parser and initialize setting.

* x86bc.c (yasm_x86__ea_create_expr): Transform val+RIP to val wrt RIP when
using the GAS parser (this is how GAS interprets "expr(%rip)").

* x86id.re: Too many changes to enumerate in detail.  Add new modifiers for
GAS suffixes.  Start using them in a couple instructions.  Split check_id
into subfunctions (still one entry point at present).
(yasm_x86__finalize_insn): Support new modifiers, reverse operands, derefs.

* yasm.c (main): Change all undef to extern when using GAS parser (this is
default GAS behavior).

svn path=/trunk/yasm/; revision=1239