Quiet a -Wcomma warning.

Clang's got a warning -Wcomma that warns about possible unintentional uses of
the comma operator, usually where a semicolon looks itended.

I don't think there's a bug here, but a semicolon does work just as well
and reads a bit more conventionally.  Though, I'm not actually sure how this
parses, as fp = ...; glslFP = ...; or fp = (..., glsl = ...).  The second
would most definitely be a bug.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2365403002

NOTREECHECKS=true

Review-Url: https://codereview.chromium.org/2365403002
diff --git a/src/gpu/gl/GrGLProgram.cpp b/src/gpu/gl/GrGLProgram.cpp
index dd73d01..86b2372 100644
--- a/src/gpu/gl/GrGLProgram.cpp
+++ b/src/gpu/gl/GrGLProgram.cpp
@@ -111,7 +111,8 @@
     while (fp && glslFP) {
         glslFP->setData(fProgramDataManager, *fp);
         this->bindTextures(*fp, pipeline.getAllowSRGBInputs(), nextSamplerIdx);
-        fp = iter.next(), glslFP = glslIter.next();
+        fp = iter.next();
+        glslFP = glslIter.next();
     }
     SkASSERT(!fp && !glslFP);
 }