nptl/sysdeps/unix/sysv/linux/i386: enable USE___THREAD for assembler

NPTL defines errno as __thread variable. Define USE___THREAD so proper
errno assignment is used in assembly files.

This fixes segfault while building python.

Signed-off-by: Timo Teräs <timo.teras@iki.fi>
Signed-off-by: Natanael Copa <natanael.copa@gmail.com>
Signed-off-by: Austin Foxley <austinf@cetoncorp.com>

libpthread/nptl/sysdeps/unix/sysv/linux/i386/Makefile.arch

@@ -7,6 +7,7 @@
 LINUX_ARCH_DIR:=$(top_srcdir)libpthread/nptl/sysdeps/unix/sysv/linux/i386
 LINUX_ARCH_OUT:=$(top_builddir)libpthread/nptl/sysdeps/unix/sysv/linux/i386
 
+ASFLAGS += -DUSE___THREAD
 
 libpthread_SSRC = pt-vfork.S clone.S pthread_spin_unlock.S pthread_once.S
 libpthread_CSRC = pthread_spin_init.c pt-__syscall_error.c