[LLD] [COFF] Fix parsing version numbers with leading zeros

Parse the components as decimal, instead of decuding the base from
the string. This avoids ambiguity if the second number contains leading
zeros, which previously were parsed as indicating an octal number.

MS link.exe doesn't support hexadecimal numbers in the version numbers,
neither in /version nor in /subsystem.

Differential Revision: https://reviews.llvm.org/D88801