linux: Use an empty string for unmapped module names
linux: Use an empty string for unmapped module names

This may be a bug in the target program or loader, but doesn't seem
like something worth dying over. If a link_entry name is empty,
ProcessReaderLinux::InitializeModules() will fall back to using the
name of the module's mapping. In this case, the main executable's
link entry name pointed into unmapped memory, but the memory map was
able to identify it as app_process32.

Bug: crashpad:30
Change-Id: Ic6df08132271efb809bf0bc28f23a333deb20a67
Reviewed-on: https://chromium-review.googlesource.com/999301
Commit-Queue: Joshua Peraza <f5809a5e35ec7e1bd0e25cb0a0b68bb433cf6f17@chromium.org>
Reviewed-by: Mark Mentovai <f1b5a91d4d6ad523f2610114591c007e75d15084@chromium.org>

chromium/crashpad,chromium/crashpad,chromium/crashpad