Set SOVERSION to 1

We're not a framework right now and we're not planning to maintain ABI
at this point. Maybe not even source compatibility.

(cherry picked from commit d9b22de)

CMakeLists.txt

@@ -20,7 +20,7 @@ set(REQUIRED_QT_VERSION "5.2.0")
 ecm_setup_version(5.0.0
                   VARIABLE_PREFIX KFILEMETADATA
                   PACKAGE_VERSION_FILE "${CMAKE_CURRENT_BINARY_DIR}/KF5FileMetaDataConfigVersion.cmake"
-                  SOVERSION 5)
+                  SOVERSION 1)
 
 # Build dependencies
 find_package(Qt5 ${REQUIRED_QT_VERSION} REQUIRED NO_MODULE COMPONENTS Xml)