With the update of the Kconfig symbols to new naming scheme,
CONFIG_PTHREAD does not exist anymore.
Use the new CONFIG_POSIX_THREADS instead
Follow-up: #73047
Signed-off-by: Pierrick Guillaume <pierguill@gmail.com>
Some third-party modules uses 'find_package(Threads REQUIRED)' to check
if threads implementation is supported.
The original implementation tries to find threads library using various
methods (e.g. checking if pthread library is present or compiling
example program to check if the implementation is provided by libc), but
it's not able to detect pthread implementation provided by Zephyr.
Signed-off-by: Patryk Duda <patrykd@google.com>
