fix compiler detection code

Reducibility_Multiplex/Makefile

@@ -3,26 +3,33 @@ CFLAGS=-O2
 LDFLAGS=-lm -lgmp -lz
 
 
-IS_CC_GCC=$(shell $(CC) --version 2>/dev/null | grep -Eic 'gcc')
-IS_CC_CLANG=$(shell $(CC) --version | grep -Eic '(llvm|clang)') 
-IS_CC_ICC=$(shell $(CC) --version | grep -Eic 'Intel')
+CC_RUNS=$(shell \$($(CC) --version >/dev/null ))
 
+##$(info $$CC_RUNS is [${CC_RUNS}])
 
+#ifeq ($(CC_RUNS), "")
+ifdef CC_RUNS
+IS_CC_GCC=$(shell $(CC) --version 2>/dev/null | grep -Eic '(GCC)')
+##$(info $$IS_CC_GCC is [${IS_CC_GCC}])
 ifneq ($(IS_CC_GCC), 0)
 # compiler is GCC
-		CFLAGS+=-fopenmp
+CFLAGS+=-fopenmp
 else
-ifneq ($(IS_CC_CLANG), 0)
-# compiler is CLANG
-		LDFLAGS+=-lomp
-else 
-ifneq($(IS_CC_ICC), 0)
+IS_CC_ICC=$(shell $(CC) --version 2>/dev/null | grep -Eic 'Intel')
+##$(info $$IS_CC_ICC is [${IS_CC_ICC}])
+ifneq ($(IS_CC_ICC), 0)
 # compiler is Intel icc
-			CFLAGS+=-qopenmp
+CFLAGS+=-qopenmp
+else
+IS_CC_CLANG=$(shell $(CC) --version 2>/dev/null | grep -Eic '(llvm|clang)')
+##$(info $$IS_CC_CLANG is [${IS_CC_CLANG}])
+ifeq ($(IS_CC_CLANG), 1)
+# compiler is CLANG
+LDFLAGS+=-lomp
+endif
+endif
 endif
 endif
-
-
 all: reducibility_complexity
 
 clean: