Provide better scmrev defaults without .git

Use the default values from CMakeLists.txt (previously used for CPack). We
usually update these when tagging a new major version.

CMakeLists.txt

@@ -143,6 +143,14 @@ else()
 	set(DOLPHIN_VERSION_PATCH ${DOLPHIN_WC_REVISION})
 endif()
 
+# If Dolphin is not built from a Git repository, default the version info to
+# reasonable values.
+if(NOT DOLPHIN_WC_REVISION)
+	set(DOLPHIN_WC_DESCRIBE "${DOLPHIN_VERSION_MAJOR}.${DOLPHIN_VERSION_MINOR}")
+	set(DOLPHIN_WC_REVISION "${DOLPHIN_WC_DESCRIBE} (no further info)")
+	set(DOLPHIN_WC_BRANCH "master")
+endif()
+
 # Architecture detection and arch specific settings
 message(${CMAKE_SYSTEM_PROCESSOR})