app_main: silence static analyzer warnings

This silences two warnings:

frameworks/base/cmds/app_process/app_main.cpp:238:11: warning: Potential
memory leak

frameworks/base/cmds/app_process/app_main.cpp:261:9: warning: Potential
memory leak

As the (existing) comment notes, we nuke argv later in main(), so these
copies are necessary. Since these args need to live for basically the
entire life of the process, it seems pointless to go out of our way to
free them.

Bug: 27101951
Test: mma. Static analyzer warnings are gone.
Change-Id: Icbfabfede9db909f6acb274b697cb6076c3fc11f