Doc: document the new Darwin options

gcc/ChangeLog:

	* doc/invoke.texi: Document the new -nodefaultrpaths option.
	* doc/install.texi: Document the new --with-darwin-extra-rpath
	option.

Author: fxcoudert

gcc/doc/install.texi

@@ -1856,6 +1856,12 @@ particularly useful if you intend to use several versions of GCC in
 parallel.  The default is @samp{yes} for @samp{libada}, and @samp{no} for
 the remaining libraries.
 
+@item --with-darwin-extra-rpath
+This is provided to allow distributions to add a single additional
+runpath on Darwin / macOS systems. This allows for cases where the
+installed GCC library directories are then symlinked to a common
+directory outside of the GCC installation.
+
 @item @anchor{WithAixSoname}--with-aix-soname=@samp{aix}, @samp{svr4} or @samp{both}
 Traditional AIX shared library versioning (versioned @code{Shared Object}
 files as members of unversioned @code{Archive Library} files named

gcc/doc/invoke.texi

@@ -926,7 +926,7 @@ Objective-C and Objective-C++ Dialects}.
 -iframework
 -image_base  -init  -install_name  -keep_private_externs
 -multi_module  -multiply_defined  -multiply_defined_unused
--noall_load   -no_dead_strip_inits_and_terms
+-noall_load   -no_dead_strip_inits_and_terms -nodefaultrpaths
 -nofixprebinding  -nomultidefs  -noprebind  -noseglinkedit
 -pagezero_size  -prebind  -prebind_all_twolevel_modules
 -private_bundle  -read_only_relocs  -sectalign
@@ -24484,6 +24484,14 @@ an executable when linking, using the Darwin @file{libtool} command.
 This causes GCC's output file to have the @samp{ALL} subtype, instead of
 one controlled by the @option{-mcpu} or @option{-march} option.
 
+@opindex nodefaultrpaths
+@item -nodefaultrpaths
+Do not add default run paths for the compiler library directories to
+executables, modules or dynamic libraries. On macOS 10.5 and later,
+the embedded runpath is added by default unless the user adds
+@option{-nodefaultrpaths} to the link line. Run paths are needed
+(and therefore enforced) to build on macOS version 10.11 or later.
+
 @item -allowable_client  @var{client_name}
 @itemx -client_name
 @itemx -compatibility_version