Remove makefile cruft.

The files that need _GNU_SOURCE define it themselves, and bionic
now correctly takes that to imply the latest _POSIX_C_SOURCE (which
this _wasn't_ getting, leading to a missing declaration for open_memstream).

Bug: 17361504
Change-Id: Idd1c2abb6818d5216a7cdcdbaa235a113447831f
diff --git a/Android.mk b/Android.mk
index d93784e..76ad7ef 100644
--- a/Android.mk
+++ b/Android.mk
@@ -103,8 +103,6 @@
 LOCAL_C_INCLUDES_x86_64 := $(LOCAL_C_INCLUDES_x86)
 LOCAL_SRC_FILES_x86_64 := $(LOCAL_SRC_FILES_x86)
 
-LOCAL_CFLAGS := -D_GNU_SOURCE=1 -D_POSIX_SOURCE=1
-
 LOCAL_CFLAGS += \
     -DELF_HASH_TAKES_CHARP=1 \
     -DHAVE_ALARM=1 \