libc: some architectures do not require baremetal libc

When building a native application, we use the host provided libc, so do
not build minimal libc or newlib.

Signed-off-by: Alberto Escolar Piedras <alpi@oticon.com>
Signed-off-by: Anas Nashif <anas.nashif@intel.com>

lib/CMakeLists.txt

@@ -1,4 +1,6 @@
 add_subdirectory(crc)
-add_subdirectory_ifdef(CONFIG_JSON_LIBRARY json)
+add_subdirectory_ifdef(CONFIG_JSON_LIBRARY          json)
+if(NOT CONFIG_NATIVE_APPLICATION)
 add_subdirectory(libc)
+endif()
 add_subdirectory_if_kconfig(ring_buffer)

lib/libc/Kconfig

@@ -7,6 +7,7 @@
 #
 
 menu "C Library"
+depends on !NATIVE_APPLICATION
 
 config NEWLIB_LIBC
 	bool

misc/Kconfig

@@ -122,6 +122,13 @@ config CROSS_COMPILE
 	  need to set this unless you want the configured kernel build
 	  directory to select the cross-compiler automatically.
 
+config NATIVE_APPLICATION
+	bool "Build as a native host application"
+	default n
+	help
+	  Build as a native application that can run on the host and using
+	  resources and libraries provided by the host.
+
 config COMPILER_OPT
 	string
 	prompt "Custom compiler options"