posix: remove unneeded option to link with posix subsys

The CONFIG_APP_LINK_WITH_POSIX_SUBSYS option was originally
present so that internal POSIX implementation headers would be
on the include path.

There is no implicit need for any app or library to include
private POSIX headers. Instead, the standard POSIX API should
be used.

Signed-off-by: Christopher Friedt <cfriedt@meta.com>

doc/services/portability/posix/kconfig/index.rst

@@ -6,7 +6,6 @@ Configuration Options
 This is a non-exhaustive list of specific :ref:`kconfig` options relating to Zephyr's
 implementation of the POSIX API.
 
-* :kconfig:option:`CONFIG_APP_LINK_WITH_POSIX_SUBSYS`
 * :kconfig:option:`CONFIG_EVENTFD`
 * :kconfig:option:`CONFIG_EVENTFD_MAX`
 * :kconfig:option:`CONFIG_FDTABLE`

lib/posix/options/CMakeLists.txt

@@ -6,8 +6,6 @@ zephyr_syscall_header(
   posix_clock.h
 )
 
-zephyr_interface_library_named(posix_subsys)
-
 if(CONFIG_POSIX_API)
   zephyr_include_directories(${ZEPHYR_BASE}/include/zephyr/posix)
 endif()
@@ -63,6 +61,3 @@ zephyr_library_include_directories(
   ${ZEPHYR_BASE}/kernel/include
   ${ARCH_DIR}/${ARCH}/include
 )
-
-zephyr_library_link_libraries(posix_subsys)
-zephyr_library_property(ALLOW_EMPTY TRUE)

lib/posix/options/Kconfig

@@ -12,15 +12,6 @@ config POSIX_API
 	  Enable mostly-standards-compliant implementations of
 	  various POSIX (IEEE 1003.1) APIs.
 
-# The name of this option is mandated by zephyr_interface_library_named
-# cmake directive.
-config APP_LINK_WITH_POSIX_SUBSYS
-	bool "Make POSIX headers available to application"
-	default y
-	depends on POSIX_API
-	help
-	  Add POSIX subsystem header files to the 'app' include path.
-
 if POSIX_CLOCK
 
 config PTHREAD_IPC