<bits/syscall.h>: Use an arch-independent system call list on Linux
This commit changes the way the list of SYS_* system call macros is
created on Linux. glibc now contains a list of all known system
calls, and the generated <bits/syscall.h> file defines the SYS_ macro
only if the correspnding __NR_ macro is defined by the kernel headers.
As a result, glibc does not have to be rebuilt to pick up system calls
if the glibc sources already know about them. This means that glibc
can be built with older kernel headers, and if the installed kernel
headers are upgraded afterwards, additional SYS_ macros become
available as long as glibc has a record for those system calls.
hurd: Fix static initialization with -fstack-protector-strong
When linked statically, TLS initialization is not achieved before
mach_init and alike, so ssp accesses to tcbhead's stack_guard would
crash. We can just avoid using ssp in the few functions needed before
TLS is set up.
x86: Remove assembly versions of index_cpu_*/index_arch_*
Since assembly versions of HAS_CPU_FEATURE and HAS_ARCH_FEATURE have
been removed, assembly versions of index_cpu_* and index_arch_* can
also be removed.
Tested on i686 and x86-64 with and without --disable-multi-arch.
