Improve test framework: Solaris bug

The 'includeTests' function failed if /bin/bash was not available or not
the same as the Bash used to run the top test script.  This failed on
Solaris, where /usr/bin/bash is too old, and a privately-built Bash must
be used to run the test scripts.

testframework.sh

@@ -1537,7 +1537,7 @@ _tfw_find_tests() {
          local script
          _tfw_unpack_words "$include" lineno script
          local listline
-         "$_tfw_script_dir/$script" --list 2>/dev/null | while read listline; do
+         "$BASH" "$_tfw_script_dir/$script" --list 2>/dev/null | while read listline; do
             local number
             local name
             local path