fix(cm): hide `cm_init_context_by_index` from BL1

BL1 requires the context management library but does not use or
implement `cm_init_context_by_index`. This change ensures that is not
compiled into BL1, as linking with LTO enabled causes an undefined
reference for this function.

Change-Id: I4a4602843bd75bc4f47b3e0c4c5a6efce1514ef6
Signed-off-by: Chris Kay <chris.kay@arm.com>
diff --git a/include/lib/el3_runtime/context_mgmt.h b/include/lib/el3_runtime/context_mgmt.h
index f631125..7451b85 100644
--- a/include/lib/el3_runtime/context_mgmt.h
+++ b/include/lib/el3_runtime/context_mgmt.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2023, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2024, Arm Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -30,12 +30,15 @@
 void *cm_get_context(uint32_t security_state);
 void cm_set_context(void *context, uint32_t security_state);
 void cm_init_my_context(const struct entry_point_info *ep);
-void cm_init_context_by_index(unsigned int cpu_idx,
-			      const struct entry_point_info *ep);
 void cm_setup_context(cpu_context_t *ctx, const struct entry_point_info *ep);
 void cm_prepare_el3_exit(uint32_t security_state);
 void cm_prepare_el3_exit_ns(void);
 
+#if !IMAGE_BL1
+void cm_init_context_by_index(unsigned int cpu_idx,
+			      const struct entry_point_info *ep);
+#endif /* !IMAGE_BL1 */
+
 #ifdef __aarch64__
 #if IMAGE_BL31
 void cm_manage_extensions_el3(void);