* src/*: Add checks for parameters of API functions where missing.

`API functions' are functions tagged with `FT_EXPORT_DEF'.

Besides trivial fixes, the following changes are included, too.

* src/base/ftbdf.c (FT_Get_BDF_Charset_ID, FT_Get_BDF_Property): Set
error code if no service is available.

* src/base/ftinit.c (FT_Done_FreeType): Change return value for
invalid `library' parameter to `Invalid_Library_Handle'.

* src/base/ftobjs.c (FT_New_Size): Change return value for invalid
`asize' parameter to `Invalid_Argument'.

* src/base/ftoutln.c (FT_Outline_Copy): Change return value for
invalid `source' and `target' parameters to `Invalid_Outline'.
(FT_Outline_Done_Internal): Change return value for invalid
`outline' parameter to `Invalid_Outline'.
24 files changed