libc: armclang: Implement compiler printf symbols

armclang replaces calls to printf by calls to one of the symbols
__0printf, __1printf or __2printf. This patch adds new functions with
these names that internally call printf so that the Trusted Firmware can
be compiled with this compiler.

Change-Id: I06a0e3e5001232fe5b2577615666ddd66e81eef0
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Makefile

@@ -211,6 +211,10 @@ BL_COMMON_SOURCES	+=	common/bl_common.c			\
 				plat/common/${ARCH}/platform_helpers.S	\
 				${COMPILER_RT_SRCS}
 
+ifeq ($(notdir $(CC)),armclang)
+BL_COMMON_SOURCES	+=	lib/${ARCH}/armclang_printf.S
+endif
+
 INCLUDES		+=	-Iinclude				\
 				-Iinclude/bl1				\
 				-Iinclude/bl2				\
@@ -239,7 +243,6 @@ INCLUDES		+=	-Iinclude				\
 				${SPD_INCLUDES}				\
 				-Iinclude/tools_share
 
-
 ################################################################################
 # Generic definitions
 ################################################################################

lib/aarch32/armclang_printf.S

@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <asm_macros.S>
+
+/* Symbols needed by armclang */
+
+	.globl __0printf
+	.globl __1printf
+	.globl __2printf
+
+func __0printf
+__1printf:
+__2printf:
+        b	printf
+endfunc __0printf

lib/aarch64/armclang_printf.S

@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <asm_macros.S>
+
+/* Symbols needed by armclang */
+
+	.globl __0printf
+	.globl __1printf
+	.globl __2printf
+
+func __0printf
+__1printf:
+__2printf:
+        b	printf
+endfunc __0printf