Change the GetAdjustedRelPc to GetPcAdjustment.

This cleans up a bit of the Unwinder code to make it clear what's
going on.

Modify the offline unit tests to verify the pc and sp to make sure
that those values get computed correctly.

Test: Passes unit tests.
Test: Passes 137-cfi art tests.
Change-Id: I0787a1d77b8726d3defd08f31c7476f6798f8d0d
diff --git a/libunwindstack/tests/RegsFake.h b/libunwindstack/tests/RegsFake.h
index cd7f2ff..ab23194 100644
--- a/libunwindstack/tests/RegsFake.h
+++ b/libunwindstack/tests/RegsFake.h
@@ -47,7 +47,7 @@
 
   bool Is32Bit() { return false; }
 
-  uint64_t GetAdjustedPc(uint64_t rel_pc, Elf*) override { return rel_pc - 2; }
+  uint64_t GetPcAdjustment(uint64_t, Elf*) override { return 2; }
 
   bool StepIfSignalHandler(uint64_t, Elf*, Memory*) override { return false; }
 
@@ -77,7 +77,7 @@
 
   ArchEnum Arch() override { return ARCH_UNKNOWN; }
 
-  uint64_t GetAdjustedPc(uint64_t, Elf*) override { return 0; }
+  uint64_t GetPcAdjustment(uint64_t, Elf*) override { return 0; }
   void SetFromRaw() override {}
   bool SetPcFromReturnAddress(Memory*) override { return false; }
   bool StepIfSignalHandler(uint64_t, Elf*, Memory*) override { return false; }