Use "-x c" when compiling hc files

rules/hs-suffix-rules-srcdir.mk

@@ -55,10 +55,10 @@ endif
 # .hs->.o rule, I don't know why --SDM
 
 $1/$2/build/%.$$($3_osuf) : $1/$4/%.hc
-	$$(CC) $$($1_$2_$3_ALL_CC_OPTS) -c $$< -o $$@
+	$$(CC) $$($1_$2_$3_ALL_CC_OPTS) -x c -c $$< -o $$@
 
 $1/$2/build/%.$$($3_osuf) : $1/$2/build/%.hc
-	$$(CC) $$($1_$2_$3_ALL_CC_OPTS) -c $$< -o $$@
+	$$(CC) $$($1_$2_$3_ALL_CC_OPTS) -x c -c $$< -o $$@
 
 # $1/$2/build/%.$$($3_osuf) : $1/$2/build/%.$$($3_way_)hc
 # 	$$($1_$2_HC) $$($1_$2_$3_ALL_HC_OPTS) -c $$< -o $$@