Use Link Time Optimisation whenever possible (#6967)

cmake/warnings.cmake

@@ -64,7 +64,6 @@ add_warning(init-self)
 add_warning(bool-compare)
 add_warning(logical-not-parentheses)
 add_warning(logical-op)
-add_warning(maybe-uninitialized)
 add_warning(misleading-indentation)
 # `no-` prefix is part of warning name(i.e. doesn't mean we are disabling it)
 add_warning(no-return-local-addr)
@@ -84,3 +83,6 @@ no_warning(comma-subscript)
 no_warning(ambiguous-reversed-operator)
 no_warning(restrict)
 no_warning(free-nonheap-object)
+if(CMAKE_CXX_COMPILER_ID MATCHES "GNU")
+  no_warning(stringop-overflow)
+endif()