Prevent GCC warnings

```
regexec.c: In function ‘reset_match_cache’:
regexec.c:1259:56: warning: suggest parentheses around ‘-’ inside ‘<<’ [-Wparentheses]
 1259 |     match_cache[k1 >> 3] &= ((1 << (8 - (k2 & 7) - 1)) - 1 << ((k2 & 7) + 1)) | ((1 << (k1 & 7)) - 1);
      |                              ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
regexec.c:1269:60: warning: suggest parentheses around ‘-’ inside ‘<<’ [-Wparentheses]
 1269 |         match_cache[k2 >> 3] &= ((1 << (8 - (k2 & 7) - 1)) - 1 << ((k2 & 7) + 1));
      |                                  ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
regexec.c: In function ‘find_cache_index_table’:
regexec.c:1192:11: warning: ‘m’ may be used uninitialized [-Wmaybe-uninitialized]
 1192 |   if (!(0 <= m && m < num_cache_table && table[m].addr == p)) {
      |         ~~^~~~
regexec.c: In function ‘match_at’:
regexec.c:1238:12: warning: ‘m1’ is used uninitialized [-Wuninitialized]
 1238 |   if (table[m1].addr < pbegin && m1 + 1 < num_cache_table) m1++;
      |            ^
regexec.c:1218:39: note: ‘m1’ was declared here
 1218 |   int l = 0, r = num_cache_table - 1, m1, m2;
      |                                       ^~
regexec.c:1239:12: warning: ‘m2’ is used uninitialized [-Wuninitialized]
 1239 |   if (table[m2].addr > pend && m2 - 1 > 0) m2--;
      |            ^
regexec.c:1218:43: note: ‘m2’ was declared here
 1218 |   int l = 0, r = num_cache_table - 1, m1, m2;
      |                                           ^~
```

0 files changed, 0 insertions, 0 deletions