improve the scripts for building unit tests:

* support unsupported/
* use egrep instead of grep, properly escape special chars.

scripts/buildtests.in

@@ -0,0 +1,24 @@
+#!/bin/bash
+
+if [ $# == 0 -o $# -ge 3 ]
+then
+  echo "usage: ./buildtests regexp [jobs]"
+  echo "  makes tests matching the regexp, with [jobs] concurrent make jobs"
+  exit 0
+fi
+
+TESTSLIST="${EIGEN_TESTS_LIST}"
+
+targets_to_make=`echo "$TESTSLIST" | egrep "$1" | sed s/^/test_/g | xargs echo`
+
+if [ $# == 1 ]
+then
+  make $targets_to_make
+  exit $?
+fi
+
+if [ $# == 2 ]
+then
+  make -j $2 $targets_to_make
+  exit $?
+fi