Fix test that fails on i686:

https://bitbucket.org/cffi/cffi/issues/382

This is a squashed version of these commits:
https://bitbucket.org/cffi/cffi/commits/ef09637b2314
https://bitbucket.org/cffi/cffi/commits/7a76a3815340

diff -r 99940f1f5402 testing/cffi0/test_function.py
--- a/testing/cffi0/test_function.py	Tue Feb 27 21:18:33 2018 +0100
+++ b/testing/cffi0/test_function.py	Sun Nov 11 16:26:23 2018 +0100
@@ -45,14 +45,14 @@
         assert x != math.sin(1.23)    # rounding effects
         assert abs(x - math.sin(1.23)) < 1E-6
 
-    def test_sin_no_return_value(self):
+    def test_lround_no_return_value(self):
         # check that 'void'-returning functions work too
         ffi = FFI(backend=self.Backend())
         ffi.cdef("""
-            void sin(double x);
+            void lround(double x);
         """)
         m = ffi.dlopen(lib_m)
-        x = m.sin(1.23)
+        x = m.lround(1.23)
         assert x is None
 
     def test_dlopen_filename(self):
le>
<table class='tabs'><tr><td>
<a href='/guix/about/'>about</a><a href='/guix/'>summary</a><a href='/guix/refs/?id=48d5818a0e9cf9ceec4e1b76ee4309e048e5f57e'>refs</a><a class='active' href='/guix/log/gnu/packages/musl.scm'>log</a><a href='/guix/tree/gnu/packages/musl.scm?id=48d5818a0e9cf9ceec4e1b76ee4309e048e5f57e'>tree</a><a href='/guix/commit/gnu/packages/musl.scm?id=48d5818a0e9cf9ceec4e1b76ee4309e048e5f57e'>commit</a><a href='/guix/diff/gnu/packages/musl.scm?id=48d5818a0e9cf9ceec4e1b76ee4309e048e5f57e'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/musl.scm'>
<input type='hidden' name='id' value='48d5818a0e9cf9ceec4e1b76ee4309e048e5f57e'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=48d5818a0e9cf9ceec4e1b76ee4309e048e5f57e'>root</a>/<a href='/guix/log/gnu?id=48d5818a0e9cf9ceec4e1b76ee4309e048e5f57e'>gnu</a>/<a href='/guix/log/gnu/packages?id=48d5818a0e9cf9ceec4e1b76ee4309e048e5f57e'>packages</a>/<a href='/guix/log/gnu/packages/musl.scm?id=48d5818a0e9cf9ceec4e1b76ee4309e048e5f57e'>musl.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/musl.scm?id=48d5818a0e9cf9ceec4e1b76ee4309e048e5f57e&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2018-09-09 15:01:54 +0200'>2018-09-09</span></td><td><a href='/guix/commit/gnu/packages/musl.scm?id=bb105673b88cea5c290ea9a16094ce29fcf0f475'>gnu: musl: Update to 1.1.20.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2018-02-23 16:00:04 +0100'>2018-02-23</span></td><td><a href='/guix/commit/gnu/packages/musl.scm?id=78d6524aeb0d04c47582e28710dcc6308af489f7'>gnu: musl: Use HTTPS home page.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2018-02-23 16:00:04 +0100'>2018-02-23</span></td><td><a href='/guix/commit/gnu/packages/musl.scm?id=4b971dde8f987c0762d9e5bac9243ce930881376'>gnu: musl: Update to 1.1.19.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2017-11-20 18:59:54 -0500'>2017-11-20</span></td><td><a href='/guix/commit/gnu/packages/musl.scm?id=ebde40a14aa3e48f4dd8e2c342452cceca336486'>gnu: musl: Update to 1.1.18.</a><span class='msg-avail'>...</span></td><td>Leo Famulari</td></tr>
<tr><td><span title='2017-10-19 17:37:25 -0400'>2017-10-19</span></td><td><a href='/guix/commit/gnu/packages/musl.scm?id=9ccce799102433b0ae2b480ac0c4f96794808199'>gnu: musl: Update to 1.1.17.</a><span class='msg-avail'>...</span></td><td>Leo Famulari</td></tr>