Fix linkerconfig_backward_compatibility_test

The current GetValue() falls back to GetProperty(). This makes the test
show different result on different running environment. For consistent
test result, MockVariables() now overrides all product/vendor variables.

Bug: n/a
Test: atest --host linkerconfig_backward_compatibility_test
      atest linkerconfig_backward_compatibility_test

Change-Id: I4b7533e10058b0236a8aef4c54fbb58f3bec0ccc
1 file changed