dev-cpp/cpp-httplib: USE=test requires other flags

The build system, when adding tests, doesn't separate based
on the flags, so we require all those flags to be ON when
testing. It isn't really worth it to improve build system.

Signed-off-by: Arthur Zamarin <arthurzam@gentoo.org>

dev-cpp/cpp-httplib/cpp-httplib-0.28.0.ebuild

@@ -25,6 +25,7 @@ LICENSE="MIT"
 SLOT="0/$(ver_cut 0-2)"  # soversion
 
 IUSE="brotli ssl test zlib zstd"
+REQUIRED_USE="test? ( brotli zlib zstd )"
 RESTRICT="!test? ( test )"
 
 RDEPEND="