Use conservative permissions when creating files in ART

Use 644 permissions by default so that only the owner has write-rights.

Bug: 130821293
Test: host run-test & gtest
Merged-In: Ic4dae399a5bfe862aff3d8614c45b38044d805db
Merged-In: I09eab9749d1ce5872ecaf7d5a80fc45c9c708853
Change-Id: I09eab9749d1ce5872ecaf7d5a80fc45c9c708853
1 file changed