$ ./check-doc-syntax.sh
Checking documentation for incorrect syntax
./cairo-types-private.h (148): WARNING: cairo_hash_entry_t: missing 'Since' field (is it a private type?)
./cairo-types-private.h (161): WARNING: cairo_hash_entry_t: not found
./cairo-types-private.h (175): WARNING: cairo_lcd_filter_t: missing 'Since' field (is it a private type?)
./cairo-cache-private.h (85): WARNING: cairo_cache_entry_t: missing 'Since' field (is it a private type?)
./cairo-region.c (857): WARNING: cairo_region_overlap_t: not found
./cairo-raster-source-pattern.c (62): WARNING: SECTION:cairo-raster-source 'Since' field in non-public element

The warnings about missing 'Since' fields are fixed by changing the
documentation comment so that the script can see that these are private types.

The documentation for cairo_region_overlap_t gets moved to cairo.h, just like
e.g. the documentation for cairo_status_t.

The 'Since' field from the SECTION:cairo-raster-source is removed, because this
kind of field is needed on the individual functions and structs, not on the
section.

Thanks to Bryce Harrington for bringing this up!

Signed-off-by: Uli Schlachter <psychon@znc.in>
Tested-by: Bryce Harrington <b.harrington@samsung.com>