Performance Optimization: replace flag checks with macros.

[soasme]

This should reduce the number of execution instructions for issue 15.

--------------------------------------------------------------------------------
Ir
--------------------------------------------------------------------------------
401,588,183 (100.0%)  PROGRAM TOTALS

--------------------------------------------------------------------------------
Ir                    file:function
--------------------------------------------------------------------------------
345,401,053 (86.01%)  peppapeg.c:P4_NeedLoosen [/app/a.out]
 25,019,000 ( 6.23%)  peppapeg.c:P4_NeedSquash [/app/a.out]
  4,617,160 ( 1.15%)  ???:_int_free [/usr/lib64/libc-2.28.so]
  3,382,226 ( 0.84%)  ???:malloc [/usr/lib64/ld-2.28.so]
  2,595,108 ( 0.65%)  peppapeg.c:P4_Match'2 [/app/a.out]
  1,848,485 ( 0.46%)  ???:free [/usr/lib64/ld-2.28.so]
  1,841,351 ( 0.46%)  peppapeg.c:P4_MatchLiteral [/app/a.out]
  1,712,968 ( 0.43%)  ???:__strlen_avx2 [/usr/lib64/libc-2.28.so]
  1,705,988 ( 0.42%)  peppapeg.c:P4_MatchChoice'2 [/app/a.out]
  1,518,598 ( 0.38%)  peppapeg.c:P4_Expression_dispatch'2 [/app/a.out]
  1,260,936 ( 0.31%)  ???:strdup [/usr/lib64/ld-2.28.so]
  1,098,095 ( 0.27%)  peppapeg.c:P4_MatchRepeat [/app/a.out]
  1,092,247 ( 0.27%)  peppapeg.c:P4_RaiseError [/app/a.out]
  1,016,618 ( 0.25%)  ???:__memcpy_avx_unaligned_erms [/usr/lib64/libc-2.28.so]
    865,496 ( 0.22%)  peppapeg.c:P4_MatchSequence'2 [/app/a.out]
    806,160 ( 0.20%)  peppapeg.c:P4_RescueError [/app/a.out]
    791,322 ( 0.20%)  peppapeg.c:P4_GetPosition [/app/a.out]
    671,409 ( 0.17%)  peppapeg.c:P4_DeleteToken [/app/a.out]
    470,520 ( 0.12%)  peppapeg.c:P4_PushFrame [/app/a.out]

Before PR:

# time ./a.out
real    0m0.090s
user    0m0.084s
sys     0m0.003s

PR:

real	0m0.052s
user	0m0.048s
sys	0m0.001s

[soasme]

#15