[CMake] Add warning if UMF version is set to 0.0.0

Improper version set in CMake means, our lib will be wrongly configured
and libumf.so.0.0.0 will be produced... which most likely is not expected
(unless it's a developer's build).

Author: lukaszstolarczuk

CMakeLists.txt

@@ -26,6 +26,12 @@ project(
     umf
     VERSION ${UMF_CMAKE_VERSION}
     LANGUAGES C)
+if(UMF_CMAKE_VERSION VERSION_EQUAL "0.0.0")
+    message(
+        WARNING
+            "UMF version is set to 0.0.0, which most likely is not expected! "
+            "Please checkout the git tags to get a proper version.")
+endif()
 
 if(PROJECT_VERSION_PATCH GREATER 0)
     # set extra variable for Windows dll metadata