Corrected bug finding camke on OSX with home-brew or 'official' distr…

…ibution.

makefiles/Makefile.unix

@@ -218,9 +218,13 @@ endif  # LINUX
 ifeq ($(PLATFORM),MACOSX)
   CCC = clang++ -fPIC -std=c++11 -mmacosx-version-min=$(MAC_MIN_VERSION) -stdlib=libc++
   DYNAMIC_LD = ld -arch x86_64 -bundle -flat_namespace -undefined suppress -macosx_version_min $(MAC_MIN_VERSION) -lSystem -compatibility_version 1.0 -current_version $(OR_TOOLS_VERSION)
-  ifeq (, $(shell which cmake))
+
+  CMAKE := $(shell which cmake)
+  ifeq ($(CMAKE),)
     $(warning "no cmake in $(PATH), assuming it is in /Applications ")
     CMAKE ?= /Applications/CMake.app/Contents/bin/cmake
+  else
+    $(warning "cmake found: $(CMAKE)")
   endif
   # CMAKE = /Applications/CMake.app/Contents/bin/cmake