suppress uninit error from SkStroke::strokePath in unit_tests

tools/valgrind/memcheck/suppressions.txt

 # There are four kinds of suppressions in this file.
 # 1. third party stuff we have no control over
 #
 # 2. intentional unit test errors, or stuff that is somehow a false positive
 # in our own code, or stuff that is so trivial it's not worth fixing
 #
 # 3. Suppressions for real chromium bugs that are not yet fixed.
 # These should all be in chromium's bug tracking system (but a few aren't yet).
 # Periodically we should sweep this file and the bug tracker clean by
 # running overnight and removing outdated bugs/suppressions.
@@ skipping 6213 matching lines @@
    fun:_ZN2v88internal5Debug17CallEventCallbackENS_10DebugEventENS0_6HandleINS0_6ObjectEEES5_PNS_5Debug10ClientDataE
    fun:_ZN2v88internal5Debug17ProcessDebugEventENS_10DebugEventENS0_6HandleINS0_8JSObjectEEEb
    fun:_ZN2v88internal5Debug12OnDebugBreakENS0_6HandleINS0_6ObjectEEEb
 }
 {
    bug_388668
    Memcheck:Leak
    fun:_Znw*
    fun:_ZN20data_reduction_proxy69DataReductionProxyUsageStatsTest_isDataReductionProxyUnreachable_Test8TestBodyEv
 }
+{
+   bug_392912
+   Memcheck:Uninitialized
+   fun:_ZNK8SkStroke10strokePathERK6SkPathPS0_
+   fun:_ZNK11SkStrokeRec11applyToPathEP6SkPathRKS0_
+   fun:_ZNK7SkPaint11getFillPathERK6SkPathPS0_PK6SkRect
+   fun:_ZNK6SkDraw8drawPathERK6SkPathRK7SkPaintPK8SkMatrixbb
+   fun:_ZNK6SkDraw8drawPathERK6SkPathRK7SkPaintPK8SkMatrixb
+   fun:_ZN14SkBitmapDevice8drawPathERK6SkDrawRK6SkPathRK7SkPaintPK8SkMatrixb
+   fun:_ZN8SkCanvas8drawPathERK6SkPathRK7SkPaint
+}