Add LOCAL_NO_LIBGCC.

This can be used to compile independent libraries without the need for
libgcc.a.

Change-Id: I924200995569d9a978ddbaa6ec321d80734f1374
diff --git a/core/executable_internal.mk b/core/executable_internal.mk
index 2684d51..cdaf293 100644
--- a/core/executable_internal.mk
+++ b/core/executable_internal.mk
@@ -37,7 +37,11 @@
 my_target_global_ld_dirs := $($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_GLOBAL_LD_DIRS)
 my_target_libprofile_rt := $($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_LIBPROFILE_RT)
 my_target_libgcov := $($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_LIBGCOV)
+ifeq ($(LOCAL_NO_LIBGCC),true)
+my_target_libgcc :=
+else
 my_target_libgcc := $($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_LIBGCC)
+endif
 my_target_libatomic := $($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_LIBATOMIC)
 my_target_crtbegin_dynamic_o := $($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_CRTBEGIN_DYNAMIC_O)
 my_target_crtbegin_static_o := $($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_CRTBEGIN_STATIC_O)