Regularize "NUL terminated input" --help texts

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

archival/cpio.c

@@ -74,7 +74,7 @@
 //usage:     "\n	-F FILE	Input (-t,-i,-p) or output (-o) file"
 //usage:     "\n	-R USER[:GRP]	Set owner of created files"
 //usage:     "\n	-L	Dereference symlinks"
-//usage:     "\n	-0	Input is separated by NULs"
+//usage:     "\n	-0	NUL terminated input"
 
 /* GNU cpio 2.9 --help (abridged):
 

findutils/grep.c

@@ -83,7 +83,7 @@
 //usage:     "\n	-F	PATTERN is a literal (not regexp)"
 //usage:     "\n	-E	PATTERN is an extended regexp"
 //usage:	IF_EXTRA_COMPAT(
-//usage:     "\n	-z	Input is NUL terminated"
+//usage:     "\n	-z	NUL terminated input"
 //usage:	)
 //usage:     "\n	-m N	Match up to N times per file"
 //usage:	IF_FEATURE_GREP_CONTEXT(

findutils/xargs.c

@@ -537,7 +537,7 @@ static int xargs_ask_confirmation(void)
 //usage:#define xargs_full_usage "\n\n"
 //usage:       "Run PROG on every item given by stdin\n"
 //usage:	IF_FEATURE_XARGS_SUPPORT_ZERO_TERM(
-//usage:     "\n	-0	Input is separated by NULs"
+//usage:     "\n	-0	NUL terminated input"
 //usage:	)
 //usage:	IF_FEATURE_XARGS_SUPPORT_ARGS_FILE(
 //usage:     "\n	-a FILE	Read from FILE instead of stdin"