Modify Makefile for arm yocto platform.

Makefile

+# Set DIR
+BUILD_DIR       ?= .
+SRC_DIR         ?= .
+
 # Set CROSS_COMPILE
-CROSS_COMPILE ?=
+ARCH            ?=
+CROSS_COMPILE   ?=
+
+ifeq ($(ARCH), arm)
+PKG_CONFIG_DIR  := $(PKG_CONFIG_SYSROOT_DIR)-native/usr/bin
+PKG_CONFIG      := $(PKG_CONFIG_DIR)/pkg-config
+else
+PKG_CONFIG      := pkg-config
+endif
 
 # Make variables (CC, etc...)
 CC            = $(CROSS_COMPILE)gcc
-CFLAGS        = `pkg-config --cflags gtk+-3.0`
-LIBS          = `pkg-config --libs gtk+-3.0`
+
+CFLAGS        ?=
+LIBS          ?=
+
+ifeq ($(ARCH), arm)
+CFLAGS        += -march=armv7-a -mfpu=neon -mfloat-abi=hard -mcpu=cortex-a9 \
+                 --sysroot=$(PKG_CONFIG_SYSROOT_DIR)
+endif
+
+GLIB_CFLAGS   =
+GTK3_CFLAGS   = $(shell $(PKG_CONFIG) --cflags gtk+-3.0)
+
+CFLAGS        += $(GLIB_CFLAGS) $(GTK3_CFLAGS)
+
+ifeq ($(ARCH), arm)
+INCLUDES      := \
+                 -I$(PKG_CONFIG_SYSROOT_DIR)/usr/include \
+                 -I$(PKG_CONFIG_SYSROOT_DIR)-native/usr/include
+endif
+
+GLIB_LIBS     = -lglib-2.0
+GTK3_LIBS     = $(shell $(PKG_CONFIG) --libs gtk+-3.0)
+
+LIBS          += $(GLIB_LIBS) $(GTK3_LIBS)
 
 # Objects
 objects       = main.o
@@ -14,10 +48,11 @@ all: timemanager
 
 # Build objects
 timemanager: $(objects)
+	$(CC) $(CFLAGS) -o $@ $< $(LIBS)
 
 # Temp objects
-%.o: %.c
-	$(CC) $(CFLAGS) $< -o $@ $(LIBS)
+%.o: $(SRC_DIR)/%.c
+	$(CC) $(CFLAGS) $(INCLUDES) -c -o $@ $<
 
 # Clean
 .PHONY: clean