Enable armv7 core file writing for Mach-O binaries.  
The problems with the dyld all image infos struct 
seems to be specific to arm64.

llvm-svn: 221760
diff --git a/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp b/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
index 2c4b241..796b92c 100644
--- a/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
+++ b/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
@@ -5437,11 +5437,12 @@
             bool make_core = false;
             switch (target_arch.GetMachine())
             {
-                  // arm and arm64 core file writing is having some problem with writing
-                  // down the dyld shared images info struct and/or the main executable binary.
-//                case llvm::Triple::arm:
+                  // arm64 core file writing is having some problem with writing  down the 
+                  // dyld shared images info struct and/or the main executable binary. May
+                  // turn out to be a debugserver problem, not sure yet.
 //                case llvm::Triple::aarch64:
 
+                case llvm::Triple::arm:
                 case llvm::Triple::x86:
                 case llvm::Triple::x86_64:
                     make_core = true;