meson.build: remove -DCURL_DISABLE_TYPECHECK

meson.build: remove -DCURL_DISABLE_TYPECHECK

Commit 9371322a60 ("sparse: suppress some \"using sizeof on a function\"
warnings", 2013-10-06) used target-specific variable assignments to add
-DCURL_DISABLE_TYPECHECK to SPARSE_FLAGS for each of the files affected
by the "typecheck-gcc.h" warnings. (http-push.c, http.c, http-walker.c
and remote-curl.c).

These warnings are only issued by sparse, and not by gcc, so we do not
want to disable the 'type checking' for non-sparse targets. The meson
build does not provide any sparse targets, so there is no need to use
the CURL_DISABLE_TYPECHECK preprocessor flag with the c compiler.

In order to re-enable the curl 'type checking' in the meson build, remove
the assignment of -DCURL_DISABLE_TYPECHECK to libgit_c_args.

Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>