Failed Tests on 32-bit Platform

This was reported by Girvin on the mailing list.

In the progression from 4.1.3 to 4.2.2, test failures have crept into the 32-bit platform. This is perhaps not a surprise as the developers are using 64-bit platforms and I don't think we're testing on 32-bit platforms.

<= 4.1.3: (Passed 51, failed 1, skipped 0 out of 52 tests)
 * gcode3 test fails.

4.2.0: (Passed 89, failed 2, skipped 1 out of 92 tests)
 * object_list has quite a few warnings on castings,
 * gcode3 test fails,
 * drc-clearance-misc test fails,
 * buried-vias test is skipped due to a missing input file.

4.2.1: (Passed 97, failed 4, skipped 3 out of 104 tests)
 * object_list has quite a few warnings on castings,
 * gcode3 test fails,
 * png101 fails
 * png102 fails
 * gsvit1 is skipped with missing golden files
 * nelma1 is skipped with missing golden files
 * drc-clearance-buriedvias-buriedvias is skipped with a missing source file
 * drc-clearance-misc test fails,

4.2.2: (Passed 97, failed 4, skipped 3 out of 104 tests)
(same as 4.2.1)