binutils: refactor check_relocs
binutils, glibc, gcc: support TLS copy relocations

This allows the local-exec model to be used for any non-PIC TLS reference,
even if it cannot be proven at compile time that the access binds locally.
It essentially obviates the need for IE -> LE relaxations.
gcc: disable inapplicable test case

We don't signal SIGFPE on division by zero.
glibc: improve memset
glibc: fix memcpy link error; improve memcpy
gcc: fix ICEs generating PIEs