tests: assume automake quotes 'like this', not `like this'

* t/add-missing.tap: Here.  This slightly simplifies and/or enhances
some grepping checks on automake diagnostic.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>

diff --git a/t/add-missing.tap b/t/add-missing.tap
index 6f16a0a..902ff3b 100755 (executable)
--- a/t/add-missing.tap
+++ b/t/add-missing.tap
@@ -169,11 +169,11 @@ check_ ()
     for f in $files; do
       command_ok_ \
         "$pfx warn about missing file $f" \
-        grep "required file ['\`]$build_aux/$f' not found" stderr
+        $FGREP "required file '$build_aux/$f' not found" stderr
       # Suggest the user to use '--add-missing'.
       command_ok_ \
         "$pfx suggest --add-missing for $f" \
-        grep ".*--add-missing.* install .*$f" stderr
+        grep ".*--add-missing.* install .*'$f'" stderr
     done
     # No files should be automatically installed by automake if it
     # is not told to.
@@ -192,7 +192,7 @@ check_ ()
     for f in $files; do
       command_ok_ \
         "$pfx report installation of $f" \
-        grep ": installing ['\`]$build_aux/$f'$" stderr
+        $FGREP ": installing '$build_aux/$f'" stderr
     done
     # Only the expected files should be installed.  But automake always
     # require 'missing' and 'install-sh', so account for them.