NaCl docs: mention static libraries for SJLJ

This recently came up on our mailing list, and isn't quite obvious.

R=sbc@chromium.org
BUG= none

Review URL: https://codereview.chromium.org/940503003

Cr-Commit-Position: refs/heads/master@{#317114}

1 files changed, 13 insertions, 6 deletions

diff --git a/native_client_sdk/src/doc/reference/pnacl-c-cpp-language-support.rst b/native_client_sdk/src/doc/reference/pnacl-c-cpp-language-support.rst
index 2324774..1a87dff 100644
--- a/native_client_sdk/src/doc/reference/pnacl-c-cpp-language-support.rst
+++ b/native_client_sdk/src/doc/reference/pnacl-c-cpp-language-support.rst
@@ -176,12 +176,19 @@ C++ Exception Handling
 ======================
 
 PNaCl currently supports C++ exception handling through ``setjmp()`` and
-``longjmp()``, which can be enabled with the ``--pnacl-exceptions=sjlj``
-linker flag. Exceptions are disabled by default so that faster and
-smaller code is generated, and ``throw`` statements are replaced with
-calls to ``abort()``. The usual ``-fno-exceptions`` flag is also
-supported. PNaCl will support full zero-cost exception handling in the
-future.
+``longjmp()``, which can be enabled with the ``--pnacl-exceptions=sjlj`` linker
+flag (set with ``LDFLAGS`` when using Make). Exceptions are disabled by default
+so that faster and smaller code is generated, and ``throw`` statements are
+replaced with calls to ``abort()``. The usual ``-fno-exceptions`` flag is also
+supported, though the default is ``-fexceptions``. PNaCl will support full
+zero-cost exception handling in the future.
+
+.. note:: When using naclports_ or other prebuilt static libraries, you don't
+          need to recompile because the exception handling support is
+          implemented at link time (when all the static libraries are put
+          together with your application).
+
+.. _naclports: https://code.google.com/p/naclports
 
 NaCl supports full zero-cost C++ exception handling.