tests: fix unindent to use printf not echo for script.

[Ralf Wildenhues]

I'm applying this patch in a new bugfix branch on top of
v1.11-316-g78992b3 to fix roughly 50 new testsuite failures
when /bin/sh is dash or Solaris sh, and merging to maint,
branch-1.11 and master as appropriate.

This is a bit of a stop-gap, as it would be nicer to have an echo
function or so, but that sort of solution does not commutate with the
changes towards using a better shell for tests, and anyway would only be
for efficiency: nowadays printf is always available (it might just be
buggy).

Cheers,
Ralf

    tests: fix unindent to use printf not echo for script.
    
    * tests/defs: Use printf rather than echo, as the latter may
    interpret the backslashes in the sed script.  Fixes test
    failures with dash as /bin/sh.

diff --git a/tests/defs b/tests/defs
index cf0b495..f6237d3 100644
--- a/tests/defs
+++ b/tests/defs
@@ -170,7 +170,7 @@ commented_sed_unindent_prog='
 unindent ()
 {
   if test x"$sed_unindent_prog" = x; then
-    sed_unindent_prog=`echo "$commented_sed_unindent_prog" | sed -e "s/  *# 
.*//"`
+    sed_unindent_prog=`printf '%s\n' "$commented_sed_unindent_prog" | sed -e 
"s/  *# .*//"`
   fi
   sed "$sed_unindent_prog" ${1+"$@"}
 }