Fix building on windows without cl.exe

rebar.config.script

@@ -88,8 +88,12 @@ WinSetupGCC = fun(OpenCLDir) ->
 			       4 -> E0;
 			       8 -> AddConf("WIN_TARGET", "-DWIN_X64", E0)
 			   end,
+		      CC = case GetEnv("CC") of
+			       false -> "gcc";
+			       EnvCC -> EnvCC
+			   end,
 
-		      GCCConf =[{"win32", "CC" , GetEnv("CC")},
+		      GCCConf =[{"win32", "CC" , CC},
 				{"win32", "DRV_CC_TEMPLATE",
 				 "$CC -c $CFLAGS $DRV_CFLAGS $PORT_IN_FILES -o $PORT_OUT_FILE"},
 				{"win32", "DRV_LINK_TEMPLATE",
@@ -163,7 +167,7 @@ SetupWin32 = fun(OpenCLDir) ->
 		     %% Do we want to compile with Microsoft's toolchain
 		     case os:find_executable("cl.exe") of
 			 false ->
-			     os:find_executable("gcc") orelse 
+			     (os:find_executable("gcc") == false) andalso 
 				 Error("No known compiler found",[]),
 			     WinSetupGCC(OpenCLDir);
 			 _ ->