sh: Avoid possible echo options in a testcase.

tools/regression/bin/sh/builtins/getopts1.0

@@ -1,6 +1,6 @@
 # $FreeBSD$
 
-echo '-1-'
+printf -- '-1-\n'
 set -- -abc
 getopts "ab:" OPTION
 echo ${OPTION}
@@ -11,7 +11,7 @@ echo ${OPTION}
 # ksh93 20090505; pdksh 5.2.14p2; mksh R39c; bash 4.1 PL7; and zsh 4.3.10.
 # all recognize that "b" is missing its argument on the *first* iteration
 # of 'getopts' and do not produce the "a" in $OPTION.
-echo '-2-'
+printf -- '-2-\n'
 set -- -ab
 getopts "ab:" OPTION
 echo ${OPTION}
@@ -19,7 +19,7 @@ getopts "ab:" OPTION
 echo ${OPTION}
 
 # The 'shift' is aimed at causing an error.
-echo '-3-'
+printf -- '-3-\n'
 shift 1
 getopts "ab:" OPTION
 echo ${OPTION}