[dsymutil] Fix __LINKEDIT vmsize in dsymutil upgrade path

[steven_wu]

Summary

dsymutil upgrade path can change the size of segment and it needs to update
the vmsize of the segment to reflect the size change.

rdar://problem/30290714

[friss]

vmsize shouldn't matter as we're not executing this file, but llvm-objdump got more picky recently. LGTM

llvm/trunk/tools/dsymutil/MachOUtils.cpp

static void transferSegmentAndSections(
   if (StringRef("__DWARF") == Segment.segname)
     return;
 
   Segment.fileoff = Segment.filesize = 0;
 
   if (StringRef("__LINKEDIT") == Segment.segname) {
     Segment.fileoff = LinkeditOffset;
     Segment.filesize = LinkeditSize;
+    // Resize vmsize by rounding to the page size.
+    Segment.vmsize = alignTo(LinkeditSize, 0x1000);
   }
 
   // Check if the end address of the last segment and our current
   // start address leave a sufficient gap to store the __DWARF
   // segment.
   uint64_t PrevEndAddress = EndAddress;
   EndAddress = alignTo(EndAddress, 0x1000);
   if (GapForDwarf == UINT64_MAX && Segment.vmaddr > EndAddress &&