Fix some clang compilation issues.

Use expected inline behavior with clang.

GCC defaults to -std=gnu90, giving C89 inline semantics with GNU
extensions. Clang defaults to C99. Explicitly use gnu90.

Mark an unused parameter as __unused.

Fix some incorrect casts.

Change-Id: I05b95585d5e3688eda71769b63b6b8a9237bcaf4
diff --git a/libcutils/Android.mk b/libcutils/Android.mk
index 12a3bf9..5a4be93 100644
--- a/libcutils/Android.mk
+++ b/libcutils/Android.mk
@@ -151,7 +151,7 @@
 
 LOCAL_C_INCLUDES := $(libcutils_c_includes)
 LOCAL_STATIC_LIBRARIES := liblog
-LOCAL_CFLAGS += $(targetSmpFlag) -Werror
+LOCAL_CFLAGS += $(targetSmpFlag) -Werror -std=gnu90
 LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk
 include $(BUILD_STATIC_LIBRARY)