Fix error on windows:

c:\buildbot\lldb-windows-x86\lldb-windows-x86\llvm\tools\lldb\source\symbol\goastcontext.cpp(906) : warning C4715: 'lldb_private::GoASTContext::GetBitSize' : not all control paths return a value
c:\buildbot\lldb-windows-x86\lldb-windows-x86\llvm\tools\lldb\source\symbol\goastcontext.cpp(1175) : error C4716: 'lldb_private::GoASTContext::ConvertStringToFloatValue' : must return a value

llvm-svn: 247647
diff --git a/lldb/source/Symbol/GoASTContext.cpp b/lldb/source/Symbol/GoASTContext.cpp
index a7f93fc..6bd3380 100644
--- a/lldb/source/Symbol/GoASTContext.cpp
+++ b/lldb/source/Symbol/GoASTContext.cpp
@@ -903,6 +903,7 @@
         default:
             assert(false);
     }
+    return 0;
 }
 
 lldb::Encoding
@@ -1172,6 +1173,7 @@
 GoASTContext::ConvertStringToFloatValue(void *type, const char *s, uint8_t *dst, size_t dst_size)
 {
     assert(false);
+    return 0;
 }
 //----------------------------------------------------------------------
 // Dumping types