Skip NativeCall TakeUint16 test on FreeBSD

See #1619

t/04-nativecall/02-simple-args.t

@@ -48,15 +48,25 @@ is TakeInt64(0xFFFFFFFFFF), 9, 'passed int64 0xFFFFFFFFFF';
 sub TakeUint8(uint8) returns int32 is native('./02-simple-args') { * }
 sub TakeUint16(uint16) returns int32 is native('./02-simple-args') { * }
 sub TakeUint32(uint32) returns int32 is native('./02-simple-args') { * }
-#
-# For some reason, on OS X with clang, the following two tests fail with -O3
-# specified.  One can only assume this is some weird compiler issue (tested
-# on Apple LLVM version 6.1.0 (clang-602.0.49) (based on LLVM 3.6.0svn).
-#
 if $*DISTRO.name eq 'macosx' {
+    #
+    # For some reason, on OS X with clang, the following two tests fail with -O3
+    # specified.  One can only assume this is some weird compiler issue (tested
+    # on Apple LLVM version 6.1.0 (clang-602.0.49) (based on LLVM 3.6.0svn).
+    #
     skip("Cannot test TakeUint8(0xFE) on OS X with -O3");
     skip("Cannot test TakeUint16(0xFFFE) on OS X with -O3");
 }
+elsif $*DISTRO.name eq 'freebsd' {
+    #
+    # For some reason, on FreeBSD with clang, the second test fails unless
+    # MoarVM is built with -O0 specified. Tested on FreeBSD 11.1-RELEASE-p4
+    # with Clang version 4.0.0 (tags/RELEASE_400/final 297347) (based on LLVM
+    # 4.0.0).
+    #
+    is TakeUint8(0xFE), 10, 'passed uint8 0xFE';
+    skip("Cannot test TakeUint16(0xFFFE) on FreeBSD without -O0");
+}
 else {
     is TakeUint8(0xFE),        10, 'passed uint8 0xFE';
     is TakeUint16(0xFFFE),     11, 'passed uint16 0xFFFE';