libstdc++: Remove obfuscating typedefs in <regex>

libstdc++: Remove obfuscating typedefs in <regex>

There is no benefit to using _SizeT instead of size_t, and IterT tells
you less about the type than const _CharT*. This removes some unhelpful
typedefs.

Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:

	* include/bits/regex_automaton.h (_NFA_base::_SizeT): Remove.
	* include/bits/regex_compiler.h (_Compiler::_IterT): Remove.
	* include/bits/regex_compiler.tcc: Likewise.
	* include/bits/regex_scanner.h (_Scanner::_IterT): Remove.
	* include/bits/regex_scanner.tcc: Likewise.