upgrade the patched Qt to v4.8.7

As Qt v4.8.7 is the last release in the 4.8 series, the upcoming
0.12.3 release is also likely to be the last in the 0.12 series.

CHANGELOG.md

@@ -1,5 +1,6 @@
 v0.12.3 (unreleased)
 ----------------------
+* **[qt]** upgrade the patched Qt to v4.8.7
 * removed support for CentOS 5 builds
 * update OpenSSL to 1.0.2a and xz to 5.2.1
 * downgrade libpng to 1.2.53

qt

@@ -1 +1 @@
-Subproject commit 48e71c19c7fc67517fb3dca6d42eacb57341c9ba
+Subproject commit 4f2ca071e0fe7b7397238ad64b1b24ddfd4f520e