[LLDB][Reliability] Fix accessing invalid iterator

[fixathon]

Summary

Using invalidated vector iterator is at best a UB and could crash depending on STL implementation.
Fixing via minimal changes to preserve the existing code style.

Coverity warning 1454828 (scan.coverity.com)

[JDevlieghere]

LGTM

lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOSXDYLD.cpp

for (uint32_t idx = 0; idx < image_infos.size(); ++idx) {
     // Remove this image_infos from the m_all_image_infos.  We do the
     // comparison by address rather than by file spec because we can have many
     // modules with the same "file spec" in the case that they are modules
     // loaded from memory.
     //
     // Also copy over the uuid from the old entry to the removed entry so we
     // can use it to lookup the module in the module list.
 
-    ImageInfo::collection::iterator pos, end = m_dyld_image_infos.end();
-    for (pos = m_dyld_image_infos.begin(); pos != end; pos++) {
+    bool found = false;
+
+    for (ImageInfo::collection::iterator pos = m_dyld_image_infos.begin();
+         pos != m_dyld_image_infos.end(); pos++) {
       if (image_infos[idx].address == (*pos).address) {
         image_infos[idx].uuid = (*pos).uuid;
 
         // Add the module from this image_info to the "unloaded_module_list".
         // We'll remove them all at one go later on.
 
         ModuleSP unload_image_module_sp(
             FindTargetModuleForImageInfo(image_infos[idx], false, nullptr));
         if (unload_image_module_sp.get()) {
           // When we unload, be sure to use the image info from the old list,
           // since that has sections correctly filled in.
           UnloadModuleSections(unload_image_module_sp.get(), *pos);
           unloaded_module_list.AppendIfNeeded(unload_image_module_sp);
         } else {
           if (log) {
             LLDB_LOGF(log, "Could not find module for unloading info entry:");
             image_infos[idx].PutToLog(log);
           }
         }
 
         // Then remove it from the m_dyld_image_infos:
 
         m_dyld_image_infos.erase(pos);
+        found = true;
         break;
       }
     }
 
-    if (pos == end) {
+    if (!found) {
       if (log) {
         LLDB_LOGF(log, "Could not find image_info entry for unloading image:");
         image_infos[idx].PutToLog(log);
       }
     }
   }
   if (unloaded_module_list.GetSize() > 0) {
     if (log) {