Remove IS_IN_librt

Replace with IS_IN (librt).  Generated code unchanged on x86_64

        * include/mqueue.h: Use IS_IN instead of IS_IN_librt.
        * nptl/pthreadP.h: Likewise.
        * sysdeps/unix/sysv/linux/aarch64/sysdep-cancel.h: Likewise.
        * sysdeps/unix/sysv/linux/alpha/sysdep-cancel.h: Likewise.
        * sysdeps/unix/sysv/linux/arm/sysdep-cancel.h: Likewise.
        * sysdeps/unix/sysv/linux/hppa/nptl/sysdep-cancel.h: Likewise.
        * sysdeps/unix/sysv/linux/i386/sysdep-cancel.h: Likewise.
        * sysdeps/unix/sysv/linux/ia64/sysdep-cancel.h: Likewise.
        * sysdeps/unix/sysv/linux/ia64/sysdep.h: Likewise.
        * sysdeps/unix/sysv/linux/m68k/sysdep-cancel.h: Likewise.
        * sysdeps/unix/sysv/linux/microblaze/sysdep-cancel.h: Likewise.
        * sysdeps/unix/sysv/linux/mips/mips64/sysdep-cancel.h: Likewise.
        * sysdeps/unix/sysv/linux/mips/sysdep-cancel.h: Likewise.
        * sysdeps/unix/sysv/linux/not-cancel.h: Likewise.
        * sysdeps/unix/sysv/linux/powerpc/powerpc32/sysdep-cancel.h: Likewise.
        * sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep-cancel.h: Likewise.
        * sysdeps/unix/sysv/linux/s390/s390-32/sysdep-cancel.h: Likewise.
        * sysdeps/unix/sysv/linux/s390/s390-64/sysdep-cancel.h: Likewise.
        * sysdeps/unix/sysv/linux/sh/sysdep-cancel.h: Likewise.
        * sysdeps/unix/sysv/linux/sparc/sparc32/sysdep-cancel.h: Likewise.
        * sysdeps/unix/sysv/linux/sparc/sparc64/sysdep-cancel.h: Likewise.
        * sysdeps/unix/sysv/linux/tile/sysdep-cancel.h: Likewise.
        * sysdeps/unix/sysv/linux/tile/waitpid.S: Likewise.
        * sysdeps/unix/sysv/linux/x86_64/sysdep-cancel.h: Likewise.

sysdeps/unix/sysv/linux/ia64/sysdep.h

@@ -62,7 +62,7 @@
 
 #if defined USE_DL_SYSINFO \
 	&& (!defined NOT_IN_libc \
-	    || defined IS_IN_libpthread || defined IS_IN_librt)
+	    || defined IS_IN_libpthread || IS_IN (librt))
 # define IA64_USE_NEW_STUB
 #else
 # undef IA64_USE_NEW_STUB