Math: work around GCC 4.9 crash in Android NDK.

Seems to be only in case of this particular function in the test and
nowehere else. Won't bother investigating further.

src/Magnum/Math/Test/QuaternionTest.cpp

@@ -399,6 +399,13 @@ void QuaternionTest::matrix() {
     CORRADE_COMPARE(Quaternion::fromMatrix(m4), q4);
 }
 
+/* The crappy 4.9 20140827 (prerelease) in Android NDK segfaults when
+   optimizing the following function. Dialing down the optimization helps. No
+   problem when calling Math::lerp() anywhere else, so I won't dig further.
+   Fuck this. */
+#if defined(CORRADE_TARGET_ANDROID) && __GNUC__*100 + __GNUC_MINOR__*10 + __GNUC_PATCHLEVEL__ == 490
+#pragma GCC push_options
+#pragma GCC optimize("O0")
 void QuaternionTest::lerp() {
     Quaternion a = Quaternion::rotation(Deg(15.0f), Vector3(1.0f/Constants<Float>::sqrt3()));
     Quaternion b = Quaternion::rotation(Deg(23.0f), Vector3::xAxis());
@@ -416,6 +423,8 @@ void QuaternionTest::lerp() {
     Quaternion lerp = Math::lerp(a, b, 0.35f);
     CORRADE_COMPARE(lerp, Quaternion({0.119127f, 0.049134f, 0.049134f}, 0.990445f));
 }
+#pragma GCC pop_options
+#endif
 
 void QuaternionTest::slerp() {
     Quaternion a = Quaternion::rotation(Deg(15.0f), Vector3(1.0f/Constants<Float>::sqrt3()));