Now that all warnings are taken care of, add warning flag -Wshadow to
configure.
Note: Enabling this flag for C++ generates some useless warnings about
some function parameters shadowing class member function names. So, only
enabling this warning for C code.
Change-Id: I53ffb763483fec675a3358c5e64a737a03b93eb1
Change the name of source files to replace "vpx" with "aom".
Change occurences of "vpx" in the code to "aom".
Change-Id: I002c0eaa2c350cf1a895bf01bea5788c61328027