build: change libsecp version from 0.1 to 0.1.0-pre

configure.ac

@@ -1,5 +1,15 @@
 AC_PREREQ([2.60])
-AC_INIT([libsecp256k1],[0.1])
+
+# The package (a.k.a. release) version is based on semantic versioning 2.0.0 of
+# the API. All changes in experimental modules are treated as
+# backwards-compatible and therefore at most increase the minor version.
+define(_PKG_VERSION_MAJOR, 0)
+define(_PKG_VERSION_MINOR, 1)
+define(_PKG_VERSION_BUILD, 0)
+define(_PKG_VERSION_IS_RELEASE, false)
+
+AC_INIT([libsecp256k1],m4_join([.], _PKG_VERSION_MAJOR, _PKG_VERSION_MINOR, _PKG_VERSION_BUILD)m4_if(_PKG_VERSION_IS_RELEASE, [true], [], [-pre]),[https://github.com/bitcoin-core/secp256k1/issues],[libsecp256k1],[https://github.com/bitcoin-core/secp256k1])
+
 AC_CONFIG_AUX_DIR([build-aux])
 AC_CONFIG_MACRO_DIR([build-aux/m4])
 AC_CANONICAL_HOST