patch 9.1.0946: cross-compiling fails on osx-arm64

patch 9.1.0946: cross-compiling fails on osx-arm64

Problem:  cross-compiling fails on osx-arm64
Solution: use vim_cv_timer_create_with_lrt() instead of
          vim_cv_timer_create_works() (Brandon Maier)

Cross-compiling to osx-arm64 fails with the following

  In file included from json.c:17:
  In file included from ./vim.h:457:
  ./macros.h:304:24: error: expected identifier or '('
    304 |      static inline int isnan(double x)
        |                        ^
  .../MacOSX11.0.sdk/usr/include/math.h:165:7: note: expanded from macro 'isnan'
    165 |     ( sizeof(x) == sizeof(float)  ? __inline_isnanf((float)(x))
        |       ^

This can be traced back to ./configure incorrectly detecting the
compiler support for `isnan()`, from the config.log:

  configure:14567: checking for isnan()
  configure:14588: arm64-apple-darwin20.0.0-clang <...> -L$PREFIX/lib conftest.c  -lncurses -ltinfo -lrt >&5
  ld: library not found for -lrt
  arm64-apple-darwin20.0: error: linker command failed with exit code 1 (use -v to see invocation)

The `-lrt` linking is added by ./configure script when it detects
compiler support for `timer_create()`. On the osx-arm64 platform
`timer_create()` works but does not link with `-lrt`. This results in
the following settings from config.log:

  vim_cv_timer_create=yes
  vim_cv_timer_create_with_lrt=no
  vim_cv_timer_create_works=yes

But the configure.ac incorrectly uses `timer_create_works` to add
`-lrt`, instead of using `timer_create_with_lrt`.

fixes: https://github.com/conda-forge/vim-feedstock/pull/1664
closes: #16242

Signed-off-by: Brandon Maier <brandon.maier@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>