[AIX][TLS][clang] Add -maix-small-local-dynamic-tls clang option (#88829)

This patch adds the clang portion of an AIX-specific option to inform
the
compiler that it can use a faster access sequence for the local-dynamic
TLS model (formally named aix-small-local-dynamic-tls).

This patch mainly references Amy's work on small local-exec TLS support.