Merge r1775199, r1775664 from trunk:

Fix strict Host: header checking on EBCDIC

on zOS, isascii() really means 7 bit ascii, but our strings
are in ebcdic for 99.95% of the lifetime of the server.



remove initial isascii check entirely

We are already checking an even narrower set of characters
just below.


Submitted by: covener
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1775827 13f79535-47bb-0310-9956-ffa450edef68