[base] Fix ppem size overflow.

Fixes #1086.

* src/base/ftobjs.c (FT_Request_Metrics): Add return value.
Check whether ppem values fit into unsigned short values.
(FT_Request_Size): Updated.

* include/freetype/internal/ftobjs.h: Updated.

* src/cff/cffobjs.c (cff_size_request), src/cid/cidobjs.c
(cid_size_request), src/truetype/ttdriver.c (tt_size_request),
src/type1/t1objs.c (T1_Size_Request): Updated.
6 files changed