libphobos: Update libtool version to 2:0:0

This is so that the library is not to conflict with gcc-10.

libphobos/ChangeLog:

	* configure: Regenerate.
	* configure.ac (libtool_VERSION): Update to 2:0.0.
diff --git a/libphobos/configure b/libphobos/configure
index 4c1116d..de6d367 100755
--- a/libphobos/configure
+++ b/libphobos/configure
@@ -15501,7 +15501,7 @@
 
 
 # Libdruntime / phobos soname version
-libtool_VERSION=1:0:0
+libtool_VERSION=2:0:0
 
 
 # Set default flags (after DRUNTIME_WERROR!)