[llvm] [Object,ELF] Implement PN_XNUM extension for program headers (PR #162288)

[James Henderson via llvm-commits]

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@@ -278,9 +278,45 @@ class ELFFile {
   std::vector<Elf_Shdr> FakeSections;
   SmallString<0> FakeSectionStrings;
 
+  // When the number of program headers is >= 0xffff, the actual number is
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jh7370 wrote:

Here and below, use PN_XNUM (for program headers) or SHN_LORESERVE (for section headers) instead of 0xffff/0xff00 respectively.

https://github.com/llvm/llvm-project/pull/162288