[llvm-symbolizer] Allow more flexible usage of -e.

addr2line allows -e to be grouped with other options; it also allows it
to prefix the value. Thus, all the following usages are possible:

  * addr2line -f -e <bin> <addr>
  * addr2line -fe <bin> <addr>
  * addr2line -f e<bin> <addr>
  * addr2line -fe<bin> <addr>

This patch adds the same for llvm-symbolizer.

Differential Revision: https://reviews.llvm.org/D60196

llvm-svn: 357676