lib/libc: Add FULL_LIBC_SUPPORTED helper Kconfig symbol

This symbol is selected when the target has any full libc available. This
allows tests to filter on this condition. It doesn't depend on whether the
application actually selects that library, only whether requesting a full C
library would work.

Signed-off-by: Keith Packard <keithp@keithp.com>

Author: keith-packard

Kconfig.zephyr

@@ -316,6 +316,7 @@ config CODING_GUIDELINE_CHECK
 
 config NATIVE_APPLICATION
 	bool "Build as a native host application"
+	select FULL_LIBC_SUPPORTED
 	help
 	  Build as a native application that can run on the host and using
 	  resources and libraries provided by the host.

lib/libc/Kconfig

@@ -10,6 +10,13 @@ config REQUIRES_FULL_LIBC
 	  Select a C library implementation that provides a complete C library
 	  implementation, rather than the subset provided by MINIMAL_LIBC.
 
+config FULL_LIBC_SUPPORTED
+	bool
+	help
+	  Selected when the target has at least one C library that offers a
+	  complete implementation and which would be selected when
+	  REQUIRES_FULL_LIBC is set.
+
 config MINIMAL_LIBC_SUPPORTED
 	bool
 	default y
@@ -20,6 +27,7 @@ config NEWLIB_LIBC_SUPPORTED
 	bool
 	default y
 	depends on "$(TOOLCHAIN_HAS_NEWLIB)" = "y"
+	select FULL_LIBC_SUPPORTED
 	help
 	  Selected when the target has support for the newlib C library