dev-util/cargo-c: fix build with >=libgit2-1.8.0

libgit2-sys crate has a upper bound for <1.8.0 and refuses
to build otherwise, but not seeing(?) any issues with it.

Just a quick emergency fix, will likely be fixed next libgit2-sys
version. Kept full version in the sed's path rather than a glob
to force re-checking this when the crate is bumped.

Alternatively could drop LIBGIT2_NO_VENDOR or set an upper bound
in RDEPEND, but does not seem necessary.

Signed-off-by: Ionen Wolkens <ionen@gentoo.org>

dev-util/cargo-c/cargo-c-0.9.30.ebuild

@@ -370,6 +370,10 @@ src_unpack() {
 	if [[ -n ${MY_P} ]] ; then
 		tar -xf "${DISTDIR}"/"${MY_P}.crate" -C "${WORKDIR}" || die
 	fi
+
+	# libgit2-sys unnecessarily(?) requests <libgit2-1.8.0, bump to 2 for now
+	sed -e '/range_version/s/1\.8\.0/2/' \
+		-i "${ECARGO_VENDOR}"/libgit2-sys-0.16.2+1.7.2/build.rs || die
 }
 
 src_configure() {