Fix ELF architecture offset for x86_64

The current offset results in ELF binaries returning an `#arch` of
`:dunno`.

Also, skip the `check_binary_arches` audit on the generic OS.

Library/Homebrew/formula_cellar_checks.rb

@@ -316,6 +316,8 @@ module FormulaCellarChecks
 
   def check_binary_arches(formula)
     return unless formula.prefix.directory?
+    # There is no `binary_executable_or_library_files` method for the generic OS
+    return if !OS.mac? && !OS.linux?
 
     keg = Keg.new(formula.prefix)
     mismatches = keg.binary_executable_or_library_files.reject do |file|

Library/Homebrew/os/linux/elf.rb

@@ -33,7 +33,7 @@ module ELFShim
   private_constant :ARCHITECTURE_POWERPC
   ARCHITECTURE_ARM = 0x28
   private_constant :ARCHITECTURE_ARM
-  ARCHITECTURE_X86_64 = 0x62
+  ARCHITECTURE_X86_64 = 0x3E
   private_constant :ARCHITECTURE_X86_64
   ARCHITECTURE_AARCH64 = 0xB7
   private_constant :ARCHITECTURE_AARCH64