fixed SPIR-V int->uint conversion

Bug: skia:
Change-Id: I31c035ac5839d60521ee9d8f73c879776ef5d22d
Reviewed-on: https://skia-review.googlesource.com/24621
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
diff --git a/src/sksl/SkSLSPIRVCodeGenerator.h b/src/sksl/SkSLSPIRVCodeGenerator.h
index 1ce9d0c..4500abb 100644
--- a/src/sksl/SkSLSPIRVCodeGenerator.h
+++ b/src/sksl/SkSLSPIRVCodeGenerator.h
@@ -153,6 +153,8 @@
 
     SpvId writeIntConstructor(const Constructor& c, OutputStream& out);
 
+    SpvId writeUIntConstructor(const Constructor& c, OutputStream& out);
+
     /**
      * Writes a matrix with the diagonal entries all equal to the provided expression, and all other
      * entries equal to zero.