Fix the test suite so that individual *.tests files can be run ala
  COMMAND=sort ./sort.tests
So we can compare against non-busybox versions, and possibly our testsuite
will be useful to somebody like the Linux Test Project someday.

Redid testing.sh to add new command, "optional", to skip tests that require
certain features.  (use: `optional FEATURE_SORT_BIG`, or `optional ""` to
stop skipping.)  Note that optional is a NOP if the environment variable
"OPTIONFLAGS" is blank, so although we're marking up the tests with busybox
specific knowledge, it doesn't interfere with running the tests without
busybox.

Moved setting the "OPTIONFLAGS" environment variable to runtest.  Philosophy:
busybox-specific stuff belongs in runtest; both testing.sh and the tests
themselves should be as busybox-agnostic as possible.

Moved detecting that a command isn't in busybox at all (hence skipping the
entire command.tests file) to runtests.  Rationale: optional can't currently
test for more than one feature at a time, so if we clear anything with
optional "" we might perform tests we don't want to.

Marked up busybox.tests to know which tests need CAT enabled.  Fixed up other
tests to be happy with new notation.

I suspect egrep should be appended to grep.  It's a sub-feature, really...
diff --git a/testsuite/testing.sh b/testsuite/testing.sh
index 83727f6..c1002a6 100755
--- a/testsuite/testing.sh
+++ b/testsuite/testing.sh
@@ -4,10 +4,18 @@
 #
 # License is GPLv2, see LICENSE in the busybox tarball for full license text.
 
-# The "testing" function uses one environment variable:
-#	COMMAND = command to execute
+# This file defines two functions, "testing" and "optionflag"
+
+# The "testing" function must have the following environment variable set:
+#    COMMAND = command to execute
 #
-# The function takes five arguments:
+# The following environment variables may be set to enable optional behavior
+# in "testing":
+#    VERBOSE - Print the diff -u of each failed test case.
+#    DEBUG - Enable command tracing.
+#    SKIP - do not perform this test (this is set by "optionflag")
+#
+# The "testing" function takes five arguments:
 #	$1) Description to display when running command
 #	$2) Command line arguments to command"
 #	$3) Expected result (on stdout)"
@@ -17,39 +25,31 @@
 # The exit value of testing is the exit value of the command it ran.
 #
 # The environment variable "FAILCOUNT" contains a cumulative total of the
-# 
+# number of failed tests.
 
-verbose=0
-debug=0
-force=0
-for x in "$@" ; do
-	case "$x" in
-	-v|--verbose)  verbose=1; shift;;
-	-d|--debug)    debug=1; shift;;
-	-f|--force)    force=1; shift;;
-	--)            break;;
-	-*)            echo "Unknown option '$x'"; exit 1;;
-	*)             break;;
-	esac
-done
-
-if [ -n "$VERBOSE" ] ; then
-	verbose=1
-fi
-if [ -n "$DEBUG" ] ; then
-	debug=1
-fi
+# The "optional" function is used to skip certain tests, ala:
+#   optionflag CONFIG_FEATURE_THINGY
+#
+# The "optional" function checks the environment variable "OPTIONFLAGS",
+# which is either empty (in which case it always clears SKIP) or
+# else contains a colon-separated list of features (in which case the function
+# clears SKIP if the flag was found, or sets it to 1 if the flag was not found).
 
 export FAILCOUNT=0
+export SKIP=
 
 # Helper functions
 
-config_is_set ()
+optional()
 {
-  local uc_what=$(echo ${1?} | tr a-z A-Z)
-  grep -q "^[ 	]*CONFIG_${uc_what}" ${bindir:-..}/.config || \
-    grep -q "^[ 	]*BB_CONFIG_${uc_what}" ${bindir:-..}/.config
-  return $?
+  option="$OPTIONFLAGS" | egrep "(^|:)$1(:|\$)"
+  # Not set?
+  if [[ -z "$1" || -z "$OPTIONFLAGS" || ${#option} -ne 0 ]]
+  then
+    SKIP=""
+    return
+  fi
+  SKIP=1
 }
 
 # The testing function
@@ -62,17 +62,14 @@
     exit
   fi
 
-  if [ $debug -eq 1 ] ; then
+  if [ -n "$DEBUG" ] ; then
     set -x
   fi
 
-  if [ -n "$_BB_CONFIG_DEP" ] && [ ${force} -eq 0 ]
+  if [ -n "$SKIP" ]
   then
-    if ! config_is_set "$_BB_CONFIG_DEP"
-    then
-      echo "SKIPPED: $1"
-      return 0
-    fi
+    echo "SKIPPED: $1"
+    return 0
   fi
 
   echo -ne "$3" > expected
@@ -83,18 +80,19 @@
   cmp expected actual > /dev/null
   if [ $? -ne 0 ]
   then
-	((FAILCOUNT++))
-	echo "FAIL: $1"
-	if [ $verbose -eq 1 ]
-	then
-		diff -u expected actual
-	fi
+    FAILCOUNT=$[$FAILCOUNT+1]
+    echo "FAIL: $1"
+    if [ -n "$VERBOSE" ]
+    then
+      diff -u expected actual
+    fi
   else
-	echo "PASS: $1"
+    echo "PASS: $1"
   fi
   rm -f input expected actual
 
-  if [ $debug -eq 1 ] ; then
+  if [ -n "$DEBUG" ]
+  then
     set +x
   fi