* arch.h (yasm_arch_syntax_flavor): Remove.
(yasm_arch_create): Add parser and error parameters; now the arch is given
the keyword of the parser in use. The error parameter allows the caller to
find out whether it was the machine name or the parser name that was in
error.
(yasm_arch_module): Change create definition to match yasm_arch_create().
(yasm_arch_create_error): New error typedef for yasm_arch_create() errors.
* lc3barch.c (lc3b_create): Update to match new yasm_arch_create().
* x86arch.c (x86_create): Likewise.
* yasm.c (main): Use new yasm_arch_create() and handle the two kinds of
errors it can now generate. Move parser creation up in the sequence so it
happens before the arch is created.