Fixes BZ #15337.
Static builds fail with the following warning:
/home/tools/glibc/glibc/nptl/../nptl/sysdeps/unix/sysv/linux/x86_64/cancellation.S:80:
undefined reference to `__GI___pthread_unwind'
When the source is configured with --disable-hidden-plt. This is
because the preprocessor conditional in cancellation.S only checks if
the build is for SHARED, whereas hidden_def is defined appropriately
only for a SHARED build that will have symbol versioning *and* hidden
defs are enabled. The last case is false here.
9ac3b5047e