https-dns-proxy: avoid picking up host clang-tidy

Otherwise compilation fails when clang-tidy is found in the host:

-- clang-tidy found: /usr/lib/llvm/7/bin/clang-tidy

error: unknown argument: '-fhonour-copts' [clang-diagnostic-error]
error: unknown argument:'-iremap[...]:https_dns_proxy-2018-04-23'
[clang-diagnostic-error]

Signed-off-by: Eneas U de Queiroz <cotequeiroz@gmail.com>

net/https-dns-proxy/Makefile

@@ -16,6 +16,8 @@ PKG_LICENSE:=MIT
 include $(INCLUDE_DIR)/package.mk
 include $(INCLUDE_DIR)/cmake.mk
 
+CMAKE_OPTIONS += -DCLANG_TIDY_EXE=
+
 define Package/https_dns_proxy
   SECTION:=net
   CATEGORY:=Network