Add support for ECDSA P-256 with SHA256

This adds a small EC library that is capable of verifying a signature of
SHA256 with ECDSA on the NIST P-256 curve.

Change-Id: I2a16639c92a77e8e4783c47ffbc56676de56eb59
diff --git a/libmincrypt/Android.mk b/libmincrypt/Android.mk
index 090d0e5..7906986 100644
--- a/libmincrypt/Android.mk
+++ b/libmincrypt/Android.mk
@@ -1,18 +1,18 @@
 # Copyright 2008 The Android Open Source Project
 #
 LOCAL_PATH := $(call my-dir)
-include $(CLEAR_VARS)
 
+include $(CLEAR_VARS)
 LOCAL_MODULE := libmincrypt
-LOCAL_SRC_FILES := rsa.c sha.c sha256.c
+LOCAL_SRC_FILES := dsa_sig.c p256.c p256_ec.c p256_ecdsa.c rsa.c sha.c sha256.c
+LOCAL_CFLAGS := -Wall -Werror
 include $(BUILD_STATIC_LIBRARY)
 
 include $(CLEAR_VARS)
-
 LOCAL_MODULE := libmincrypt
-LOCAL_SRC_FILES := rsa.c sha.c sha256.c
+LOCAL_SRC_FILES := dsa_sig.c p256.c p256_ec.c p256_ecdsa.c rsa.c sha.c sha256.c
+LOCAL_CFLAGS := -Wall -Werror
 include $(BUILD_HOST_STATIC_LIBRARY)
 
-
 include $(LOCAL_PATH)/tools/Android.mk \
         $(LOCAL_PATH)/test/Android.mk