Fix makefile in MultiSource/UnitTests/Float (#113)

"Makefile:9: *** invalid syntax in conditional.  Stop."
The error occurred and I fixed it.

Author: IamYJLee

MultiSource/UnitTests/Float/Makefile

@@ -6,7 +6,7 @@ PARALLEL_DIRS :=
 
 # Tests in 'rounding' can run only if the target implements builtin functions
 # for rounding mode manipulation.
-ifneq (, $filter($(ARCH), X86_64 AArch64)
+ifneq (,$(filter $(ARCH), X86_64 AArch64))
 PARALLEL_DIRS += rounding
 endif