Support a map that represents gdb jit elf data.

Changes:
- Add a new flag to the libbacktrace and libunwindstack map data.
- Modify the unwinder to handle this map to use the raw pc when stepping.
- Add new unit tests for this case.

Bug: http://b/73127105
Test: Run simpleperf to unwind through jit symfiles.
Test: Run new unit tests.
Test: Run 137-cfi test on host.
Change-Id: I10bc0410680accc6d35fe51e9f1098911f667e01
diff --git a/libunwindstack/Maps.cpp b/libunwindstack/Maps.cpp
index 4c16212..e1a1a71 100644
--- a/libunwindstack/Maps.cpp
+++ b/libunwindstack/Maps.cpp
@@ -25,6 +25,7 @@
 
 #include <android-base/unique_fd.h>
 
+#include <algorithm>
 #include <cctype>
 #include <memory>
 #include <string>
@@ -209,6 +210,11 @@
   maps_.push_back(map_info);
 }
 
+void Maps::Sort() {
+  std::sort(maps_.begin(), maps_.end(),
+            [](const MapInfo* a, const MapInfo* b) { return a->start < b->start; });
+}
+
 Maps::~Maps() {
   for (auto& map : maps_) {
     delete map;