Move GetLibraryVersion function to its own module file

build/cmake/CMakeModules/GetLibraryVersion.cmake

@@ -0,0 +1,9 @@
+function(GetLibraryVersion _header _major _minor _release)
+    # Read file content
+    FILE(READ ${_header} CONTENT)
+
+    string(REGEX MATCHALL ".*define ZSTD_VERSION_MAJOR+.* ([0-9]+).*define ZSTD_VERSION_MINOR+.* ([0-9]+).*define ZSTD_VERSION_RELEASE+.* ([0-9]+)" VERSION_REGEX "${CONTENT}")
+    SET(${_major} ${CMAKE_MATCH_1} PARENT_SCOPE)
+    SET(${_minor} ${CMAKE_MATCH_2} PARENT_SCOPE)
+    SET(${_release} ${CMAKE_MATCH_3} PARENT_SCOPE)
+endfunction()