[llvm-symbolizer] Add llvm-addr2line

This adds an alias for llvm-symbolizer with different defaults so that
it can be used as a drop-in replacement for GNU's addr2line.

If a substring "addr2line" is found in the tool's name:
  * it defaults "-i", "-f" and "-C" to OFF;
  * it uses "--output-style=GNU" by default.

Differential Revision: https://reviews.llvm.org/D60067

llvm-svn: 358749
diff --git a/llvm/docs/CommandGuide/index.rst b/llvm/docs/CommandGuide/index.rst
index 9108ae6..8a6edf5 100644
--- a/llvm/docs/CommandGuide/index.rst
+++ b/llvm/docs/CommandGuide/index.rst
@@ -31,6 +31,7 @@
    llvm-profdata
    llvm-stress
    llvm-symbolizer
+   llvm-addr2line
    llvm-dwarfdump
    dsymutil
    llvm-mca