Add 'MBEDTLS_DHM_ALT' #DEFINE to library/config.h

Add 'MBEDTLS_DHM_ALT' #DEFINE to library/config.h to support alternate DHM
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 69e997f..f8594b8 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -275,6 +275,8 @@
 //#define MBEDTLS_SHA1_ALT
 //#define MBEDTLS_SHA256_ALT
 //#define MBEDTLS_SHA512_ALT
+//#define MBEDTLS_DHM_ALT
+
 /*
  * When replacing the elliptic curve module, pleace consider, that it is
  * implemented with two .c files: