LibCoreDump: Make symbolication work when .text isn't the first segment

This can happen with binaries built with Clang or with a custom linker
script.

Userland/Libraries/LibCoreDump/Backtrace.cpp

@@ -79,14 +79,18 @@ Backtrace::~Backtrace()
 
 void Backtrace::add_entry(const Reader& coredump, FlatPtr ip)
 {
-    auto* region = coredump.region_containing((FlatPtr)ip);
-    if (!region) {
+    auto* ip_region = coredump.region_containing((FlatPtr)ip);
+    if (!ip_region) {
         m_entries.append({ ip, {}, {}, {} });
         return;
     }
-    auto object_name = region->object_name();
+    auto object_name = ip_region->object_name();
     if (object_name == "Loader.so")
         return;
+    // We need to find the first region for the object, just in case
+    // the PT_LOAD header for the .text segment isn't the first one
+    // in the object file.
+    auto region = coredump.first_region_for_object(object_name);
     auto* object_info = object_info_for_region(*region);
     if (!object_info)
         return;

Userland/Libraries/LibCoreDump/Reader.cpp

@@ -137,6 +137,19 @@ const JsonObject Reader::process_info() const
     // FIXME: Maybe just cache this on the Reader instance after first access.
 }
 
+ELF::Core::MemoryRegionInfo const* Reader::first_region_for_object(StringView object_name) const
+{
+    ELF::Core::MemoryRegionInfo const* ret = nullptr;
+    for_each_memory_region_info([&ret, &object_name](auto& region_info) {
+        if (region_info.object_name() == object_name) {
+            ret = &region_info;
+            return IterationDecision::Break;
+        }
+        return IterationDecision::Continue;
+    });
+    return ret;
+}
+
 const ELF::Core::MemoryRegionInfo* Reader::region_containing(FlatPtr address) const
 {
     const ELF::Core::MemoryRegionInfo* ret = nullptr;

Userland/Libraries/LibCoreDump/Reader.h

@@ -32,6 +32,7 @@ public:
     const ELF::Image& image() const { return m_coredump_image; }
 
     Optional<FlatPtr> peek_memory(FlatPtr address) const;
+    ELF::Core::MemoryRegionInfo const* first_region_for_object(StringView object_name) const;
     const ELF::Core::MemoryRegionInfo* region_containing(FlatPtr address) const;
 
     struct LibraryData {