[Testing] Add a lot more missing instruction tests

src/xenia/cpu/ppc/testing/instr_fnmaddx.s

@@ -0,0 +1,43 @@
+test_fnmaddx_1:
+  #_ REGISTER_IN f1 2.0
+  #_ REGISTER_IN f2 3.0
+  #_ REGISTER_IN f3 4.0
+  fnmadd. f5, f1, f2, f3
+  blr
+  #_ REGISTER_OUT f5 -10.0
+  #_ REGISTER_OUT f1 2.0
+  #_ REGISTER_OUT f2 3.0
+  #_ REGISTER_OUT f3 4.0
+
+test_fnmaddx_2:
+  #_ REGISTER_IN f1 -1.5
+  #_ REGISTER_IN f2 2.0
+  #_ REGISTER_IN f3 1.0
+  fnmadd. f5, f1, f2, f3
+  blr
+  #_ REGISTER_OUT f5 2.0
+  #_ REGISTER_OUT f1 -1.5
+  #_ REGISTER_OUT f2 2.0
+  #_ REGISTER_OUT f3 1.0
+
+test_fnmaddx_3:
+  #_ REGISTER_IN f1 0.5
+  #_ REGISTER_IN f2 0.5
+  #_ REGISTER_IN f3 0.25
+  fnmadd. f5, f1, f2, f3
+  blr
+  #_ REGISTER_OUT f5 -0.5
+  #_ REGISTER_OUT f1 0.5
+  #_ REGISTER_OUT f2 0.5
+  #_ REGISTER_OUT f3 0.25
+
+test_fnmaddx_4:
+  #_ REGISTER_IN f1 0.0
+  #_ REGISTER_IN f2 100.0
+  #_ REGISTER_IN f3 5.0
+  fnmadd. f5, f1, f2, f3
+  blr
+  #_ REGISTER_OUT f5 -5.0
+  #_ REGISTER_OUT f1 0.0
+  #_ REGISTER_OUT f2 100.0
+  #_ REGISTER_OUT f3 5.0