cmake, translation: Skip source locations in TS files

Source locations do not contribute to the string's Context on Transifex
(used for hash calculation) and only trigger unnecessary diffs in
version control.

While the `filename` attribute of the `<location>` element is rendered
as "Occurrences" on Transifex, Qt's lupdate tool does not seem to set
this attribute consistently.

share/qt/translate.cmake

@@ -103,7 +103,7 @@ execute_process(
   COMMAND ${LUPDATE_EXECUTABLE}
     -no-obsolete
     -I ${PROJECT_SOURCE_DIR}/src
-    -locations relative
+    -locations none
     ${ui_files}
     ${qt_translatable_sources}
     ${PROJECT_SOURCE_DIR}/src/qt/bitcoinstrings.cpp