build: remove `MAKE_BUILD_STRINGS` function

This function causes the build message to be generated and compiled in
two different ways, with one way done inside `build_macros.mk` and the
other done inside `windows.mk`, mostly because it's done by generating
the C file on the command line.

We can instead replace this whole build message generation sequence with
a simple standard C compilation command and a normal C file.

Change-Id: I8bc136380c9585ddeec9a11154ee39ef70526f81
Signed-off-by: Chris Kay <chris.kay@arm.com>
diff --git a/services/std_svc/rmmd/trp/trp_main.c b/services/std_svc/rmmd/trp/trp_main.c
index 33f2fb0..b75483c 100644
--- a/services/std_svc/rmmd/trp/trp_main.c
+++ b/services/std_svc/rmmd/trp/trp_main.c
@@ -1,9 +1,10 @@
 /*
- * Copyright (c) 2021-2022, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2021-2024, Arm Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
+#include <common/build_message.h>
 #include <common/debug.h>
 #include <plat/common/platform.h>
 #include <services/rmm_core_manifest.h>
@@ -86,7 +87,7 @@
 /* Main function for TRP */
 void trp_main(void)
 {
-	NOTICE("TRP: %s\n", version_string);
+	NOTICE("TRP: %s\n", build_version_string);
 	NOTICE("TRP: %s\n", build_message);
 	NOTICE("TRP: Supported RMM-EL3 Interface ABI: v.%u.%u\n",
 		TRP_RMM_EL3_ABI_VERS_MAJOR, TRP_RMM_EL3_ABI_VERS_MINOR);