Module map redundant header file exclusions

[v.g.vassilev]

Landed in r281340.

include/llvm/module.modulemap

 // and codependent, and thus notionally form a single module.
 module LLVM_Backend {
   requires cplusplus
 
   module CodeGen {
     umbrella "CodeGen"
     module * { export * }
 
-    // FIXME: Why is this excluded?
-    exclude header "CodeGen/MachineValueType.h"
-
     // Exclude these; they're intended to be included into only a single
     // translation unit (or none) and aren't part of this module.
     exclude header "CodeGen/CommandFlags.h"
     exclude header "CodeGen/LinkAllAsmWriterComponents.h"
     exclude header "CodeGen/LinkAllCodegenComponents.h"
 
     // These are intended for (repeated) textual inclusion.
     textual header "CodeGen/DIEValue.def"

 module LLVM_TableGen { requires cplusplus umbrella "TableGen" module * { export * } }
 
 module LLVM_Transforms {
   requires cplusplus
   umbrella "Transforms"
   module * { export * }
 
   // FIXME: Excluded because it does bad things with the legacy pass manager.
-  exclude header "Transforms/IPO/PassManagerBuilder.h"
+  // Doesn't seem to cause any issues.
+  //exclude header "Transforms/IPO/PassManagerBuilder.h"
 }
 
 // A module covering ADT/ and Support/. These are intertwined and
 // codependent, and notionally form a single module.
 module LLVM_Utils {
   module ADT {
     requires cplusplus
 
     umbrella "ADT"
     module * { export * }
   }
 
   module Support {
     requires cplusplus
 
     umbrella "Support"
     module * { export * }
 
     // Exclude this; it's only included on Solaris.
     exclude header "Support/Solaris.h"
 
     // Exclude this; it's fundamentally non-modular.
     exclude header "Support/PluginLoader.h"
 
-    // FIXME: Mislayered?
-    exclude header "Support/TargetRegistry.h"
-
     // These are intended for textual inclusion.
     textual header "Support/ARMTargetParser.def"
     textual header "Support/AArch64TargetParser.def"
     textual header "Support/Dwarf.def"
     textual header "Support/MachO.def"
     textual header "Support/ELFRelocs/AArch64.def"
     textual header "Support/ELFRelocs/ARM.def"
     textual header "Support/ELFRelocs/AVR.def"