Fix CVE-2016-5296: Heap-buffer-overflow WRITE in rasterize_edges_1
Adapted for upstream pixman based on:

  https://hg.mozilla.org/releases/mozilla-esr45/rev/5e39c1c2fded

--- pixman-0.34.0/pixman/pixman-edge-imp.h.orig	2015-06-30 05:48:31.000000000 -0400
+++ pixman-0.34.0/pixman/pixman-edge-imp.h	2016-11-16 01:09:34.046335106 -0500
@@ -55,8 +55,9 @@
 	 *
 	 * (The AA case does a similar  adjustment in RENDER_SAMPLES_X)
 	 */
-	lx += X_FRAC_FIRST(1) - pixman_fixed_e;
-	rx += X_FRAC_FIRST(1) - pixman_fixed_e;
+	/* we cast to unsigned to get defined behaviour for overflow */
+	lx = (unsigned)lx + X_FRAC_FIRST(1) - pixman_fixed_e;
+	rx = (unsigned)rx + X_FRAC_FIRST(1) - pixman_fixed_e;
 #endif
 	/* clip X */
 	if (lx < 0)
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<tr><td><span title='2018-05-19 00:14:52 +0200'>2018-05-19</span></td><td><a href='/guix/commit/tests/uuid.scm?id=263c9941a1e523b360ca9f42d1ed6b11e6e6e285'>uuid: 'uuid' returns #f when 'string-&gt;uuid' returns #f.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-10-06 14:16:23 +0200'>2017-10-06</span></td><td><a href='/guix/commit/tests/uuid.scm?id=0b12324284f3fbf378d363070f91b794058ae570'>uuid: Fix typo in 'uuid=?' test.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-10-05 12:09:17 +0200'>2017-10-05</span></td><td><a href='/guix/commit/tests/uuid.scm?id=aed1f1b049f6e7ef9f2f2db58bdca6cd3effe94b'>uuid: Add 'uuid=?' and use it.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-09-22 18:40:57 +0200'>2017-09-22</span></td><td><a href='/guix/commit/tests/uuid.scm?id=8a7d81a5e23c4d59fbabf2550db32d4ba5572e4b'>uuid: Add a parser for FAT32 UUIDs.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-09-14 00:10:13 +0200'>2017-09-14</span></td><td><a href='/guix/commit/tests/uuid.scm?id=8f3b63b5d73c0b49139c8a20b7576732abfdeeb8'>uuid: Move tests to 'tests/uuid.scm'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>