Include `${MBEDTLS_INCLUDE_DIR}` when compiling `crypt_mbedtls.c`

Without this, mbedTLS installs in non-default install locations
that are otherwise found by the `FindmbedTLS.cmake` module are not
found by the C preprocessor at compile time.

deps/ntlmclient/CMakeLists.txt

@@ -16,6 +16,7 @@ ELSEIF(USE_HTTPS STREQUAL "OpenSSL")
 	SET(SRC_NTLMCLIENT_CRYPTO "crypt_openssl.c")
 ELSEIF(USE_HTTPS STREQUAL "mbedTLS")
 	ADD_DEFINITIONS(-DCRYPT_MBEDTLS)
+	INCLUDE_DIRECTORIES(${MBEDTLS_INCLUDE_DIR})
 	SET(SRC_NTLMCLIENT_CRYPTO "crypt_mbedtls.c")
 ELSE()
 	MESSAGE(FATAL_ERROR "Unable to use libgit2's HTTPS backend (${USE_HTTPS}) for NTLM crypto")