The macros vct_iscrlf() and vct_skipcrlf() may look at one or two bytes
after its pointer value, causing OOB reads. This would allow
http1_dissect_hdrs to wrongly see a CRLF when one wasn't there (the last
LF left over in the bufer from the previous request).

Change the macros to inline functions, and harden them by always sending
the end pointer so that they can't overflow.

vct_iscrlf() will return an int value of 0 for no [CR]LF, 1 for LF and 2
for CRLF.

vct_skipcrlf() will return the pointer having been skipped 0, 1 or 2
bytes.