libc: share time() between minimal libc and armclang libc

Introduce a place to share implementations of libc functions that
are needed by different libc versions.  Place time() in this common
location so it can be shared when building for either minimal libc or
armclang libc.

Signed-off-by: Kumar Gala <kumar.gala@intel.com>

cmake/toolchain/armclang/Kconfig

@@ -15,6 +15,7 @@ choice LIBC_IMPLEMENTATION
 
 config ARMCLANG_STD_LIBC
 	bool "ARM Compiler C library"
+	select COMMON_LIBC_TIME if POSIX_CLOCK
 	help
 	  Use the full Arm Compiler runtime libraries.
 	  A reduced Zephyr minimal libc will be used for library functionality

lib/libc/CMakeLists.txt

@@ -5,3 +5,5 @@ add_subdirectory_ifdef(CONFIG_ARMCLANG_STD_LIBC armstdc)
 add_subdirectory_ifdef(CONFIG_MINIMAL_LIBC      minimal)
 add_subdirectory_ifdef(CONFIG_NEWLIB_LIBC       newlib)
 add_subdirectory_ifdef(CONFIG_PICOLIBC          picolibc)
+
+add_subdirectory(common)

lib/libc/Kconfig

@@ -75,6 +75,7 @@ endchoice # LIBC_IMPLEMENTATION
 config HAS_NEWLIB_LIBC_NANO
 	bool
 
+rsource "common/Kconfig"
 rsource "minimal/Kconfig"
 rsource "newlib/Kconfig"
 rsource "picolibc/Kconfig"

lib/libc/common/CMakeLists.txt

@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library()
+zephyr_library_sources_ifdef(CONFIG_COMMON_LIBC_TIME source/time/time.c)

lib/libc/common/Kconfig

@@ -0,0 +1,7 @@
+# Copyright (c) 2023 Intel Corporation
+# SPDX-License-Identifier: Apache-2.0
+
+config COMMON_LIBC_TIME
+	bool
+	help
+	  common implementation of time().

lib/libc/minimal/CMakeLists.txt

@@ -33,7 +33,6 @@ zephyr_library_sources(
 
 if(CONFIG_MINIMAL_LIBC_TIME)
   zephyr_library_sources(source/time/gmtime.c)
-  zephyr_library_sources_ifdef(CONFIG_POSIX_CLOCK source/time/time.c)
 endif()
 
 zephyr_library_sources_ifdef(CONFIG_MINIMAL_LIBC_RAND source/stdlib/rand.c)

lib/libc/minimal/Kconfig

@@ -66,6 +66,7 @@ config MINIMAL_LIBC_RAND
 
 config MINIMAL_LIBC_TIME
 	bool "Time functions"
+	select COMMON_LIBC_TIME if POSIX_CLOCK
 	default y
 	help
 	  Enable time() and gmtime_r() for the minimal libc.