debuggerd: simplify output handling

Just noticed some opportunities while skimming.

Test: adb shell debuggerd $(adb shell pidof com.android.systemui)
Test: All unit tests pass (both 32 bit and 64 bit).
Test: Ran unit tests in a loop hundreds of times.
Change-Id: I428d0cf599ed603a21944b084b95594db893cbd5
2 files changed