COPYING: remove regex copyright, add PCRE copyright

We now bundle PCRE for our regular expression implementation; include
that copyright notice and remove the now-unused regular expression
copyright.

COPYING

@@ -406,30 +406,35 @@ OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 
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-The regex library (deps/regex/) is licensed under the GNU LGPL
-(available at the end of this file).
+The bundled PCRE implementation (deps/pcre/) is licensed under the BSD
+license.
 
-Definitions for data structures and routines for the regular
-expression library.
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
 
-Copyright (C) 1985,1989-93,1995-98,2000,2001,2002,2003,2005,2006,2008
-Free Software Foundation, Inc.
-This file is part of the GNU C Library.
+    * Redistributions of source code must retain the above copyright notice,
+      this list of conditions and the following disclaimer.
 
-The GNU C Library is free software; you can redistribute it and/or
-modify it under the terms of the GNU Lesser General Public
-License as published by the Free Software Foundation; either
-version 2.1 of the License, or (at your option) any later version.
+    * Redistributions in binary form must reproduce the above copyright
+      notice, this list of conditions and the following disclaimer in the
+      documentation and/or other materials provided with the distribution.
 
-The GNU C Library is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-Lesser General Public License for more details.
+    * Neither the name of the University of Cambridge nor the name of Google
+      Inc. nor the names of their contributors may be used to endorse or
+      promote products derived from this software without specific prior
+      written permission.
 
-You should have received a copy of the GNU Lesser General Public
-License along with the GNU C Library; if not, write to the Free
-Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
-02110-1301 USA.
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
 
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