Add missing LICENSE.

libdtrace-ctf is dual-licensed under the UPL and GPLv2, so we should have the
UPL license text in the source tree.

LICENSE

@@ -0,0 +1,36 @@
+The Universal Permissive License (UPL), Version 1.0
+
+Subject to the condition set forth below, permission is hereby granted
+to any person obtaining a copy of this software, associated
+documentation and/or data (collectively the "Software"), free of charge
+and under any and all copyright rights in the Software, and any and all
+patent rights owned or freely licensable by each licensor hereunder
+covering either (i) the unmodified Software as contributed to or
+provided by such licensor, or (ii) the Larger Works (as defined below),
+to deal in both
+
+(a) the Software, and
+(b) any piece of software and/or hardware listed in the lrgrwrks.txt
+file if one is included with the Software (each a “Larger Work” to which
+the Software is contributed by such licensors),
+
+without restriction, including without limitation the rights to copy,
+create derivative works of, display, perform, and distribute the
+Software and make, use, sell, offer for sale, import, export, have made,
+and have sold the Software and the Larger Work(s), and to sublicense the
+foregoing rights on either these or other terms.
+
+This license is subject to the following condition:
+The above copyright notice and either this complete permission notice or
+at a minimum a reference to the UPL must be included in all copies or
+substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+Licensed under the Universal Permissive License v 1.0 as shown at
+http://oss.oracle.com/licenses/upl.