Handle when bias is different in elf headers.

The original code assumed that the load bias in the program headers
would be exactly the same as in eh_frame/eh_frame_hdr/debug_frame.

This isn't guaranteed, so add a section bias for use when creating
a DwarfSection. In addtion, make the load bias and section bias
a signed value. There is no reason that this value needs to be positive,
so don't force it to be.

Add a new offline test that has a different load bias in eh_frame than
in the executable load.

Add additional unit tests to verify the load bias values are set properly.

Clean up the tests in ElfInterfaceTest, making all tests names follow the
same convention.

Bug: 141888859
Bug: 142094469

Test: New units and old unit tests pass on host and taimen.
Change-Id: Ib878123ab5545f0f315c749cfe0d27b012d873ee
diff --git a/libunwindstack/DwarfEhFrameWithHdr.h b/libunwindstack/DwarfEhFrameWithHdr.h
index 0e5eef7..b8dd3dd 100644
--- a/libunwindstack/DwarfEhFrameWithHdr.h
+++ b/libunwindstack/DwarfEhFrameWithHdr.h
@@ -38,7 +38,7 @@
   using DwarfSectionImpl<AddressType>::entries_offset_;
   using DwarfSectionImpl<AddressType>::entries_end_;
   using DwarfSectionImpl<AddressType>::last_error_;
-  using DwarfSectionImpl<AddressType>::load_bias_;
+  using DwarfSectionImpl<AddressType>::section_bias_;
 
   struct FdeInfo {
     AddressType pc;
@@ -61,7 +61,7 @@
     return pc + this->memory_.cur_offset() - 4;
   }
 
-  bool Init(uint64_t offset, uint64_t size, uint64_t load_bias) override;
+  bool Init(uint64_t offset, uint64_t size, int64_t section_bias) override;
 
   const DwarfFde* GetFdeFromPc(uint64_t pc) override;