[lldb] Pass execution context to CompilerType::GetByteSize - in CommandObjectMemoryRead (NFC)

Some type systems require an execution context be available when working with types
(ex: Swift). This fixes `memory read --type` to support such type systems, by passing in
an execution context to `GetByteSize()`, instead of passing null.

rdar://158968545
(cherry picked from commit b574e63)

Author: kastiglione

lldb/source/Commands/CommandObjectMemory.cpp

@@ -364,6 +364,8 @@ class CommandObjectMemoryRead : public CommandObjectParsed {
       return;
     }
 
+    ExecutionContextScope *exe_scope = m_exe_ctx.GetBestExecutionContextScope();
+
     CompilerType compiler_type;
     Status error;
 
@@ -519,7 +521,7 @@ class CommandObjectMemoryRead : public CommandObjectParsed {
         --pointer_count;
       }
 
-      auto size_or_err = compiler_type.GetByteSize(nullptr);
+      auto size_or_err = compiler_type.GetByteSize(exe_scope);
       if (!size_or_err) {
         result.AppendErrorWithFormat(
             "unable to get the byte size of the type '%s'\n%s",
@@ -639,7 +641,7 @@ class CommandObjectMemoryRead : public CommandObjectParsed {
       if (!m_format_options.GetFormatValue().OptionWasSet())
         m_format_options.GetFormatValue().SetCurrentValue(eFormatDefault);
 
-      auto size_or_err = compiler_type.GetByteSize(nullptr);
+      auto size_or_err = compiler_type.GetByteSize(exe_scope);
       if (!size_or_err) {
         result.AppendError(llvm::toString(size_or_err.takeError()));
         return;
@@ -799,7 +801,6 @@ class CommandObjectMemoryRead : public CommandObjectParsed {
       output_stream_p = &result.GetOutputStream();
     }
 
-    ExecutionContextScope *exe_scope = m_exe_ctx.GetBestExecutionContextScope();
     if (compiler_type.GetOpaqueQualType()) {
       for (uint32_t i = 0; i < item_count; ++i) {
         addr_t item_addr = addr + (i * item_byte_size);