[locale.time.get.virtuals] Use 'conversion specification'

POSIX does not define the term 'conversion directive'.

Author: jensmaurer

source/locales.tex

@@ -3534,7 +3534,7 @@
 It then reads characters starting at \tcode{s} until it encounters an error, or
 until it has extracted and assigned those \tcode{tm} members, and
 any remaining format characters,
-corresponding to a conversion directive appropriate for
+corresponding to a conversion specification appropriate for
 the POSIX function \tcode{strptime},
 formed by concatenating \tcode{'\%'},
 the \tcode{modifier} character, when non-NUL, and
@@ -3546,9 +3546,9 @@
 the function evaluates \tcode{err |= ios_base::eofbit}.
 
 \pnum
-For complex conversion directives
+For complex conversion specifications
 such as \tcode{\%c}, \tcode{\%x}, or \tcode{\%X}, or
-directives that involve the optional modifiers \tcode{E} or \tcode{O},
+conversion specifications that involve the optional modifiers \tcode{E} or \tcode{O},
 when the function is unable to unambiguously determine
 some or all \tcode{tm} members from the input sequence \range{s}{end},
 it evaluates \tcode{err |= ios_base::eofbit}.