Remove build systems other than CMake

Make it clear that CMake is the only supported build system.

Signed-off-by: Kevin Petit <kevin.petit@arm.com>

test_conformance/device_execution/Makefile

@@ -1,52 +0,0 @@
-ifdef BUILD_WITH_ATF
-ATF = -framework ATF
-USE_ATF = -DUSE_ATF
-endif
-
-SRCS = main.c \
-	device_info.cpp \
-	device_queue.cpp \
-	enqueue_block.cpp \
-	enqueue_flags.cpp \
-	enqueue_multi_queue.cpp \
-	enqueue_ndrange.cpp \
-	enqueue_wg_size.cpp \
-	execute_block.cpp \
-	host_multi_queue.cpp \
-	host_queue_order.cpp \
-	nested_blocks.cpp \
-	utils.cpp \
-	../../test_common/harness/errorHelpers.c \
-	../../test_common/harness/testHarness.c \
-	../../test_common/harness/kernelHelpers.c \
-	../../test_common/harness/typeWrappers.cpp \
-	../../test_common/harness/mt19937.c \
-		  
-DEFINES = DONT_TEST_GARBAGE_POINTERS
-
-SOURCES = $(abspath $(SRCS))
-LIBPATH += -L/System/Library/Frameworks/OpenCL.framework/Libraries
-LIBPATH += -L.
-HEADERS = 
-TARGET = test_device_execution
-INCLUDE = 
-COMPILERFLAGS = -c -Wall -g -Wshorten-64-to-32
-CC = c++
-CFLAGS = $(COMPILERFLAGS) ${RC_CFLAGS} ${USE_ATF} $(DEFINES:%=-D%) $(INCLUDE)
-CXXFLAGS = $(COMPILERFLAGS) ${RC_CFLAGS} ${USE_ATF} $(DEFINES:%=-D%) $(INCLUDE)
-LIBRARIES = -framework OpenCL -framework OpenGL -framework GLUT -framework AppKit ${ATF}
-
-OBJECTS := ${SOURCES:.c=.o}
-OBJECTS := ${OBJECTS:.cpp=.o}
-
-TARGETOBJECT =
-all: $(TARGET)
-
-$(TARGET): $(OBJECTS)
-	$(CC) $(RC_CFLAGS) $(OBJECTS) -o $@ $(LIBPATH) $(LIBRARIES)
-
-clean:
-	rm -f $(TARGET) $(OBJECTS)
-
-.DEFAULT:
-	@echo The target \"$@\" does not exist in Makefile.