[woff2] Fix SFNT table checks.

Also reduce number of SFNT table lookups.

Reported as

  https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=18065

* include/freetype/internal/wofftypes.h (WOFF2_InfoRec): Add fields
`glyf_table', `loca_table', and `head_table'.

* src/sfnt/sfwoff2.c (reconstruct_glyf): Update signature.
Use table pointers in `info' parameter.
(get_x_mins): Check `maxp_table'
Use table pointers in `info' parameter.
(reconstruct_font):  Use and set table pointers in `info' parameter.
Fix check for `glyf' and `loca' tables.
Update call to `reconstruct_glyf'.
(woff2_open_font): Updated.
3 files changed