loader: initialize all memory in the ObjectFile objects.

Some bare metal build flows seem to build binaries that we aren't necessarily
expecting. Initialize everything to 0, so we don't make any assumptions about
what is or isn't in the binary.

src/base/loader/elf_object.cc

@@ -248,6 +248,7 @@ ElfObject::ElfObject(const string &_filename, int _fd,
 
     // initialize segment sizes to 0 in case they're not present
     text.size = data.size = bss.size = 0;
+    text.baseAddr = data.baseAddr = bss.baseAddr = 0;
 
     int secIdx = 1;
     Elf_Scn *section;

src/base/loader/object_file.cc

@@ -53,7 +53,7 @@ ObjectFile::ObjectFile(const string &_filename, int _fd,
                        size_t _len, uint8_t *_data,
                        Arch _arch, OpSys _opSys)
     : filename(_filename), descriptor(_fd), fileData(_data), len(_len),
-      arch(_arch), opSys(_opSys)
+      arch(_arch), opSys(_opSys), globalPtr(0)
 {
 }