Include license in tarball.

git-svn-id: https://protobuf-c.googlecode.com/svn/trunk@316 00440858-1255-0410-a3e6-75ea37f81c3a

Makefile.am

 SUBDIRS = src
 
-EXTRA_DIST = scripts pkgwriteinfo.in CMakeLists.txt
+EXTRA_DIST = scripts pkgwriteinfo.in CMakeLists.txt LICENSE
 
 pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = libprotobuf-c.pc