disable show-your-work bit of test

It shifts a negative number left,
which UBSAN reminds us is not allowed in C++.

Cq-Include-Trybots: luci.skia.skia.primary:Test-Debian10-Clang-GCE-CPU-AVX2-x86_64-Debug-All-SkVM_ASAN
Change-Id: I955d53b677f605b3a0f6e2bd31b16e2cc2f64ac5
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/317260
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
diff --git a/tests/SkVMTest.cpp b/tests/SkVMTest.cpp
index bc9853c..4208bad 100644
--- a/tests/SkVMTest.cpp
+++ b/tests/SkVMTest.cpp
@@ -2380,7 +2380,7 @@
         0xe000'2000, 0xdc00'2400, 0xd800'2800, 0xd400'2c00,
         0xd000'3000, 0xcc00'3400, 0xc800'3800, 0xc400'3c00, 0xc000'4000
     };
-    for (int i = 0; i < 17; i++) {
+    for (int i = 0; false && i < 17; i++) {
         // Just showing our work how we got those values.
         int16_t x = i * (+1/16.0f) * 0x4000;
         REPORTER_ASSERT(r, src[i] == (uint32_t)(x|-x<<16));