S390: Optimize utf8-utf32 module.

S390: Optimize utf8-utf32 module.

This patch reworks the s390 specific module to convert between utf8 and utf32.
Now ifunc is used to choose either the c or etf3eh (with convert utf
instruction) variants at runtime.
Furthermore a new vector variant for z13 is introduced which will be build
and chosen if vector support is available at build / runtime.
The vector variants optimize input of 1byte utf8 characters. The convert utf
instruction is used if a multibyte utf8 character is found.

This patch also fixes some whitespace errors. The c variants are rejecting
UTF-16 surrogates and values above 0x10ffff now.
Furthermore, the etf3eh variants are handling the "UTF-xx//IGNORE" case now.
Before they ignored the ignore-case and always stopped at an error.

ChangeLog:

	* sysdeps/s390/s390-64/utf8-utf32-z9.c: Use ifunc to select c, etf3eh
	or new vector loop-variant.