Stop pointing to "gn help toolchain" in that very help message.

toolchain_args became a variable in commit 22227896 ("Update GN
toolchain_args to be a variable"), but the help message was copy-pasted
from when it was a separate function and referenced the toolchain
function's help message.

Remove that reference now that it is pointing to itself.

R=brettw@chromium.org,dpranke@chromium.org
BUG=634446

Review-Url: https://codereview.chromium.org/2237483002
Cr-Original-Commit-Position: refs/heads/master@{#411115}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: fcd8d221139567226dc07b8b94ebeae1f2b94134
diff --git a/tools/gn/function_toolchain.cc b/tools/gn/function_toolchain.cc
index 852d25a..69ca961 100644
--- a/tools/gn/function_toolchain.cc
+++ b/tools/gn/function_toolchain.cc
@@ -321,9 +321,8 @@
     "\n"
     "    When you specify a target using an alternate toolchain, the master\n"
     "    build configuration file is re-interpreted in the context of that\n"
-    "    toolchain (see \"gn help toolchain\"). The toolchain_args allows you\n"
-    "    to control the arguments passed into this alternate invocation of\n"
-    "    the build.\n"
+    "    toolchain. toolchain_args allows you to control the arguments\n"
+    "    passed into this alternate invocation of the build.\n"
     "\n"
     "    Any default system arguments or arguments passed in via \"gn args\"\n"
     "    will also be passed to the alternate invocation unless explicitly\n"