[llvm-nm] Fix handling of symbol types 't' 'd' 'r'

In addition, fix and convert the two tests to yaml2obj based. This
allows us to delete two executables.

X86/weak.test: 'v' was not tested
X86/init-fini.test: symbol types of __bss_start _edata _end were wrong
  GNU nm reports __init_array_start as 't', and __preinit_array_start as 'd'.
  __init_array_start is 't' just because its section ".init_array" starts with ".init"

  'd' makes more sense and allows us to drop the weird SHT_INIT_ARRAY rule.
  So, change __init_array_start to 'd' instead.

llvm-svn: 359311