make yacc usage POSIX compatible

make yacc usage POSIX compatible

config: put YACC in config.mk and use environmental variable if present

ss:
use YACC variable instead of hardcoding bison
place options before source file argument
use -b to specify file prefix instead of output file, as -o isn't POSIX
compatible, this generates ssfilter.tab.c instead of ssfilter.c
replace any references to ssfilter.c with references to ssfilter.tab.c

tc:
use -p flag to set name prefix instead of bison-specific api.prefix
directive
remove unneeded bison-specific directives
use -b instead of -o, replace references to previously generated
emp_ematch.yacc.[ch] with references to newly generated
emp_ematch.tab.[ch]

Signed-off-by: Ethan Sommer <e5ten.arch@gmail.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>