Android.mk: Add a flag to disable libjpeg

Do not build jpeg related files if LIBYUV_DISABLE_JPEG  is set to
"yes".

BUG=libyuv:693

Change-Id: If1bc4602fb843ca7b2964844b53553aa0cca551c
Reviewed-on: https://chromium-review.googlesource.com/455475Reviewed-by: Frank Barchard <fbarchard@google.com>
Commit-Queue: Vignesh Venkatasubramanian <vigneshv@google.com>

Android.mk

@@ -15,12 +15,9 @@ LOCAL_SRC_FILES := \
     source/convert_argb.cc      \
     source/convert_from.cc      \
     source/convert_from_argb.cc \
-    source/convert_jpeg.cc      \
     source/convert_to_argb.cc   \
     source/convert_to_i420.cc   \
     source/cpu_id.cc            \
-    source/mjpeg_decoder.cc     \
-    source/mjpeg_validate.cc    \
     source/planar_functions.cc  \
     source/rotate.cc            \
     source/rotate_any.cc        \
@@ -49,9 +46,17 @@ LOCAL_SRC_FILES := \
     source/scale_neon64.cc      \
     source/video_common.cc
 
-common_CFLAGS := -Wall -fexceptions -DHAVE_JPEG
-LOCAL_CFLAGS += $(common_CFLAGS)
+common_CFLAGS := -Wall -fexceptions
+ifneq ($(LIBYUV_DISABLE_JPEG), "yes")
+LOCAL_SRC_FILES += \
+    source/convert_jpeg.cc      \
+    source/mjpeg_decoder.cc     \
+    source/mjpeg_validate.cc
+common_CFLAGS += -DHAVE_JPEG
 LOCAL_SHARED_LIBRARIES := libjpeg
+endif
+
+LOCAL_CFLAGS += $(common_CFLAGS)
 LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
 LOCAL_C_INCLUDES += $(LOCAL_PATH)/include
 LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
@@ -65,6 +70,8 @@ include $(CLEAR_VARS)
 
 LOCAL_WHOLE_STATIC_LIBRARIES := libyuv_static
 LOCAL_MODULE := libyuv
+ifneq ($(LIBYUV_DISABLE_JPEG), "yes")
 LOCAL_SHARED_LIBRARIES := libjpeg
+endif
 
 include $(BUILD_SHARED_LIBRARY)