Relocate alpha from ports to libc

Also fixed the following whitespace nits to satisfy the push:

sysdeps/alpha/alphaev6/memset.S:142: space before tab in indent.
sysdeps/alpha/configure:1: new blank line at EOF.
sysdeps/alpha/fpu/e_sqrt.c:126: space before tab in indent.
sysdeps/alpha/preconfigure:1: new blank line at EOF.
sysdeps/unix/sysv/linux/alpha/syscalls.list:1: new blank line at EOF.
Update x86_64 libm-test-ulps on AMD family 21h model 1 (bug 16545).