Add a global elf cache.

Bug: 65682279

Test: Ran new unit tests.
Change-Id: I19c64614b2b11a27f58204d4cc34913c02e04c36
diff --git a/libunwindstack/tests/JitDebugTest.cpp b/libunwindstack/tests/JitDebugTest.cpp
index 1a50989..37628f8 100644
--- a/libunwindstack/tests/JitDebugTest.cpp
+++ b/libunwindstack/tests/JitDebugTest.cpp
@@ -62,7 +62,7 @@
     ElfInterfaceFake* interface = new ElfInterfaceFake(elf_memories_.back());
     elf->FakeSetInterface(interface);
     interface->FakeSetGlobalVariable("__jit_debug_descriptor", 0x800);
-    map_info->elf = elf;
+    map_info->elf.reset(elf);
 
     map_info = maps_->Get(5);
     ASSERT_TRUE(map_info != nullptr);
@@ -72,7 +72,7 @@
     interface = new ElfInterfaceFake(elf_memories_.back());
     elf->FakeSetInterface(interface);
     interface->FakeSetGlobalVariable("__jit_debug_descriptor", 0x800);
-    map_info->elf = elf;
+    map_info->elf.reset(elf);
 
     map_info = maps_->Get(6);
     ASSERT_TRUE(map_info != nullptr);
@@ -82,7 +82,7 @@
     interface = new ElfInterfaceFake(elf_memories_.back());
     elf->FakeSetInterface(interface);
     interface->FakeSetGlobalVariable("__jit_debug_descriptor", 0x800);
-    map_info->elf = elf;
+    map_info->elf.reset(elf);
   }
 
   template <typename EhdrType, typename ShdrType>