The latest glibc (glibc-2.21.90-13.fc23) is ftbfs on aarch64 

http://arm.koji.fedoraproject.org/koji/taskinfo?taskID=3014384

gcc old_pthread_cond_wait.c -c -std=gnu99 -fgnu89-inline  -O3 -Wall -Wundef -Wwrite-strings -fasynchronous-unwind-tables -fmerge-all-constants -frounding-math -g -Wstrict-prototypes   -fPIC        -I../include -I/builddir/build/BUILD/glibc-2.21-357-gb40a4e1/build-aarch64-redhat-linux/nptl  -I/builddir/build/BUILD/glibc-2.21-357-gb40a4e1/build-aarch64-redhat-linux  -I../sysdeps/unix/sysv/linux/aarch64  -I../sysdeps/aarch64/nptl  -I../sysdeps/unix/sysv/linux/generic  -I../sysdeps/unix/sysv/linux/wordsize-64  -I../sysdeps/unix/sysv/linux/include -I../sysdeps/unix/sysv/linux  -I../sysdeps/nptl  -I../sysdeps/pthread  -I../sysdeps/gnu  -I../sysdeps/unix/inet  -I../sysdeps/unix/sysv  -I../sysdeps/unix  -I../sysdeps/posix  -I../sysdeps/aarch64/fpu  -I../sysdeps/aarch64  -I../sysdeps/wordsize-64  -I../sysdeps/ieee754/ldbl-128  -I../sysdeps/ieee754/dbl-64/wordsize-64  -I../sysdeps/ieee754/dbl-64  -I../sysdeps/ieee754/flt-32  -I../sysdeps/aarch64/soft-fp  -I../sysdeps/ieee754  -I../sysdeps/generic  -I.. -I../libio -I. -nostdinc -isystem /usr/lib/gcc/aarch64-redhat-linux/5.1.1/include -isystem /usr/include  -D_LIBC_REENTRANT -include /builddir/build/BUILD/glibc-2.21-357-gb40a4e1/build-aarch64-redhat-linux/libc-modules.h -DMODULE_NAME=libpthread -include ../include/libc-symbols.h  -DPIC -DSHARED     -o /builddir/build/BUILD/glibc-2.21-357-gb40a4e1/build-aarch64-redhat-linux/nptl/old_pthread_cond_wait.os -MD -MP -MF /builddir/build/BUILD/glibc-2.21-357-gb40a4e1/build-aarch64-redhat-linux/nptl/old_pthread_cond_wait.os.dt -MT /builddir/build/BUILD/glibc-2.21-357-gb40a4e1/build-aarch64-redhat-linux/nptl/old_pthread_cond_wait.os
pthread_cond_wait.c:38:29: fatal error: bits/libc-vdso.h: No such file or directory
compilation terminated.
../o-iterator.mk:9: recipe for target '/builddir/build/BUILD/glibc-2.21-357-gb40a4e1/build-aarch64-redhat-linux/nptl/pthread_cond_wait.os' failed
make[2]: *** [/builddir/build/BUILD/glibc-2.21-357-gb40a4e1/build-aarch64-redhat-linux/nptl/pthread_cond_wait.os] Error 1
make[2]: *** Waiting for unfinished jobs....
make[2]: Leaving directory '/builddir/build/BUILD/glibc-2.21-357-gb40a4e1/nptl'
Makefile:213: recipe for target 'nptl/subdir_lib' failed
make[1]: Leaving directory '/builddir/build/BUILD/glibc-2.21-357-gb40a4e1'
Makefile:9: recipe for target 'all' failed
make[1]: *** [nptl/subdir_lib] Error 2
make: *** [all] Error 2