Build software AGL library with correct get_tls() macro for ARMv7 based platforms

This prevents crashes on snapdragon processors.
diff --git a/opengl/libagl/Android.mk b/opengl/libagl/Android.mk
index 9837845..518be8b 100644
--- a/opengl/libagl/Android.mk
+++ b/opengl/libagl/Android.mk
@@ -37,6 +37,10 @@
 	LOCAL_CFLAGS += -fstrict-aliasing
 endif
 
+ifeq ($(ARCH_ARM_HAVE_TLS_REGISTER),true)
+    LOCAL_CFLAGS += -DHAVE_ARM_TLS_REGISTER
+endif
+
 ifneq ($(TARGET_SIMULATOR),true)
     # we need to access the private Bionic header <bionic_tls.h>
     LOCAL_C_INCLUDES += bionic/libc/private