Set symbols related make variables in apexBundle's androidMkForType()

ALL_MODULES.$(my_register_name).SYMBOLIC_OUTPUT_PATH and
ALL_MODULES.$(my_register_name).ELF_SYMBOL_MAPPING_PATH variables are
used in generating symbols.zip and the elf mapping proto file. Setting
these variables in the apex bundle allows the symbols of the modules
included in the apex to be collected properly.

Test: build mainline && inspect symbols.zip
Change-Id: I08715a278e5fe508793ebee0f1e6feee1c234970