x86_64: Enable newlib retargetable locking

This commit enables the newlib retargetable locking option to allow the
Zephyr operating system to override the dummy lock functions defined
within the newlib.

Signed-off-by: Stephanos Ioannidis <[email protected]>

Author: stephanosio

configs/x86_64-zephyr-elf.config

@@ -16,6 +16,7 @@ CT_LIBC_NEWLIB_DISABLE_SUPPLIED_SYSCALLS=y
 CT_LIBC_NEWLIB_GLOBAL_ATEXIT=y
 CT_LIBC_NEWLIB_LITE_EXIT=y
 # CT_LIBC_NEWLIB_MULTITHREAD is not set
+CT_LIBC_NEWLIB_RETARGETABLE_LOCKING=y
 # CT_LIBC_NEWLIB_WIDE_ORIENT is not set
 # CT_LIBC_NEWLIB_NANO_MALLOC is not set
 # CT_LIBC_NEWLIB_NANO_FORMATTED_IO is not set
@@ -28,6 +29,7 @@ CT_LIBC_NANO_NEWLIB_DISABLE_SUPPLIED_SYSCALLS=y
 CT_LIBC_NANO_NEWLIB_GLOBAL_ATEXIT=y
 CT_LIBC_NANO_NEWLIB_LITE_EXIT=y
 # CT_LIBC_NANO_NEWLIB_MULTITHREAD is not set
+CT_LIBC_NANO_NEWLIB_RETARGETABLE_LOCKING=y
 # CT_LIBC_NANO_NEWLIB_WIDE_ORIENT is not set
 CT_LIBC_NANO_NEWLIB_NANO_MALLOC=y
 CT_LIBC_NANO_NEWLIB_NANO_FORMATTED_IO=y