llvm-pdbutil: Fix an off-by-one error.

[zturner]

Ahh yea that would do it. Ironic that I just touched this code like an hour ago for the first time in ages, and you uncovered a bug in it right at the same time.

lld/trunk/test/COFF/pdb.test

 RAW-NEXT:                 IMAGE_SCN_CNT_CODE | IMAGE_SCN_ALIGN_16BYTES | IMAGE_SCN_MEM_EXECUTE |
 RAW-NEXT:                 IMAGE_SCN_MEM_READ
 RAW-NEXT:   SC[.rdata]  | mod = 2, 0002:0000, size = {{[0-9]+}}, data crc = 0, reloc crc = 0
 RAW-NEXT:                 IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ
 RAW-NEXT:   SC[.rdata]  | mod = 2, 0002:0028, size = {{[0-9]+}}, data crc = 0, reloc crc = 0
 RAW-NEXT:                 IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ
 RAW-NEXT:   SC[.pdata]  | mod = 0, 0003:0000, size = 12, data crc = 361370162, reloc crc = 0
 RAW-NEXT:                 IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_ALIGN_4BYTES | IMAGE_SCN_MEM_READ
-RAW-NEXT:   SC[???]     | mod = 0, 0004:0000, size = {{[0-9]+}}, data crc = 264583633, reloc crc = 0
+RAW-NEXT:   SC[.xdata]  | mod = 0, 0004:0000, size = {{[0-9]+}}, data crc = 264583633, reloc crc = 0
 RAW-NEXT:                 IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_ALIGN_4BYTES | IMAGE_SCN_MEM_READ
 RAW-NOT: SC[
 RAW:                             Section Map
 RAW-NEXT: ============================================================
 
 RAW-NEXT:   Section 0000 | ovl = 0, group = 0, frame = 1, name = 65535
 RAW-NEXT:                  class = 65535, offset = 0, size =
 RAW-NEXT:                  flags = read | execute | 32 bit addr | selector

llvm/trunk/tools/llvm-pdbutil/DumpOutputStyle.cpp

for (const auto &H : Headers)
     Names.push_back(H.Name);
   return Names;
 }
 
 static void dumpSectionContrib(LinePrinter &P, const SectionContrib &SC,
                                ArrayRef<std::string> SectionNames,
                                uint32_t FieldWidth) {
   std::string NameInsert;
-  if (SC.ISect > 0 && SC.ISect < SectionNames.size()) {
+  if (SC.ISect > 0 && SC.ISect <= SectionNames.size()) {
     StringRef SectionName = SectionNames[SC.ISect - 1];
     NameInsert = formatv("[{0}]", SectionName).str();
   } else
     NameInsert = "[???]";
   P.formatLine("SC{5}  | mod = {2}, {0}, size = {1}, data crc = {3}, reloc "
                "crc = {4}",
                formatSegmentOffset(SC.ISect, SC.Off), fmtle(SC.Size),
                fmtle(SC.Imod), fmtle(SC.DataCrc), fmtle(SC.RelocCrc),