sqlite3-unicode gcc warnings

[ejurgensen]

If you add -Wall gcc complains about a few things, see below. Might be good to fix?

$ gcc -Wall -fPIC -shared src/sqlite3-unicode.c -o dist/unicode.so
src/sqlite3-unicode.c:22: warning: ignoring #pragma warning  [-Wunknown-pragmas]
   22 | #pragma warning(disable : 4305 13 90)
      | 
src/sqlite3-unicode.c:31:32: warning: multi-line comment [-Wcomment]
   31 | #define SQLITE3_UNICODE_UNACC  // ~ 30KB increase \
      |                                ^
src/sqlite3-unicode.c: In function ‘sqlite3StrNICmp’:
src/sqlite3-unicode.c:5278:12: warning: operation on ‘ua’ may be undefined [-Wsequence-point]
 5278 |         ua = GlogUpperToLower(ua);
      |            ^
src/sqlite3-unicode.c:5279:12: warning: operation on ‘ub’ may be undefined [-Wsequence-point]
 5279 |         ub = GlogUpperToLower(ub);
      |            ^
src/sqlite3-unicode.c: In function ‘sqlite3StrNICmp16’:
src/sqlite3-unicode.c:5292:12: warning: operation on ‘ua’ may be undefined [-Wsequence-point]
 5292 |         ua = GlogUpperToLower(ua);
      |            ^
src/sqlite3-unicode.c:5293:12: warning: operation on ‘ub’ may be undefined [-Wsequence-point]
 5293 |         ub = GlogUpperToLower(ub);
      |            ^
At top level:
src/sqlite3-unicode.c:4917:33: warning: ‘likeInfoAlt’ defined but not used [-Wunused-const-variable=]
 4917 | static const struct compareInfo likeInfoAlt = {'%', '_', 0, 0};
      |                                 ^~~~~~~~~~~
src/sqlite3-unicode.c:4911:33: warning: ‘globInfo’ defined but not used [-Wunused-const-variable=]
 4911 | static const struct compareInfo globInfo = {'*', '?', '[', 0};
      |                                 ^~~~~~~~
src/sqlite3-unicode.c:4340:36: warning: ‘sqlite3UpperToLower’ defined but not used [-Wunused-const-variable=]
 4340 | SQLITE_PRIVATE const unsigned char sqlite3UpperToLower[] = {
      |                                    ^~~~~~~~~~~~~~~~~~~

[nalgeon]

Finally fixed those! And a bunch of others 😅 build #159