Remove support for undocumented SpecialCaseList entries.

"global-init", "global-init-src" and "global-init-type" were originally
used to blacklist entities in ASan init-order checker. However, they
were never documented, and later were replaced by "=init" category.

Old blacklist entries should be converted as follows:
  * global-init:foo -> global:foo=init
  * global-init-src:bar -> src:bar=init
  * global-init-type:baz -> type:baz=init

llvm-svn: 222401