float codeview, msf, pdb layers up as regular codebase layers, and out of converter-specific code; clangify some builds

src/coff/coff.h

@@ -11,6 +11,16 @@ typedef U32 COFF_TimeStamp;
 
 #pragma pack(push,1)
 
+typedef struct COFF_Guid COFF_Guid;
+struct COFF_Guid
+{
+  U32 data1;
+  U16 data2;
+  U16 data3;
+  U32 data4;
+  U32 data5;
+};
+
 typedef U16 COFF_Flags;
 enum
 {