apply --match to image file names too, like we do for .skps

This should make skipping an image much cheaper.

Before:
   $ time out/Release/nanobench --images resources/ --match sdkjlfasjlfds
        4.65 real         4.41 user         0.19 sys
   $ time out/Release/nanobench --images resources/ --match sdkjlfasjlfds
        0.05 real         0.03 user         0.01 sys

The effect should be much more dramatic when there are more images to skip (e.g. on the bots).
This cuts about 6 minutes off the Debug CQ trybot.

BUG=skia:4768
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1577873002

Review URL: https://codereview.chromium.org/1577873002
diff --git a/bench/nanobench.cpp b/bench/nanobench.cpp
index b791ab7..cfac6be 100644
--- a/bench/nanobench.cpp
+++ b/bench/nanobench.cpp
@@ -743,6 +743,9 @@
             fSourceType = "image";
             fBenchType = "skcodec";
             const SkString& path = fImages[fCurrentCodec];
+            if (SkCommandLineFlags::ShouldSkip(FLAGS_match, path.c_str())) {
+                continue;
+            }
             SkAutoTUnref<SkData> encoded(SkData::NewFromFileName(path.c_str()));
             SkAutoTDelete<SkCodec> codec(SkCodec::NewFromData(encoded));
             if (!codec) {
@@ -810,11 +813,14 @@
         }
 
         // Run the DecodingBenches
-        while (fCurrentImage < fImages.count()) {
+        for (; fCurrentImage < fImages.count(); fCurrentImage++) {
             fSourceType = "image";
             fBenchType = "skimagedecoder";
+            const SkString& path = fImages[fCurrentImage];
+            if (SkCommandLineFlags::ShouldSkip(FLAGS_match, path.c_str())) {
+                continue;
+            }
             while (fCurrentColorType < fColorTypes.count()) {
-                const SkString& path = fImages[fCurrentImage];
                 SkColorType colorType = fColorTypes[fCurrentColorType];
                 fCurrentColorType++;
                 // Check if the image decodes to the right color type
@@ -827,7 +833,6 @@
                 }
             }
             fCurrentColorType = 0;
-            fCurrentImage++;
         }
 
         // Run the BRDBenches
@@ -856,12 +861,15 @@
         //         these tests are sufficient to provide good coverage of our scaling options.
         const uint32_t sampleSizes[] = { 1, 2, 4, 8, 16, 32, 64 };
         const uint32_t minOutputSize = 512;
-        while (fCurrentBRDImage < fImages.count()) {
+        for (; fCurrentBRDImage < fImages.count(); fCurrentBRDImage++) {
+            const SkString& path = fImages[fCurrentBRDImage];
+            if (SkCommandLineFlags::ShouldSkip(FLAGS_match, path.c_str())) {
+                continue;
+            }
             while (fCurrentBRDStrategy < (int) SK_ARRAY_COUNT(strategies)) {
                 fSourceType = "image";
                 fBenchType = strategies[fCurrentBRDStrategy].fName;
 
-                const SkString& path = fImages[fCurrentBRDImage];
                 const SkBitmapRegionDecoder::Strategy strategy =
                         strategies[fCurrentBRDStrategy].fStrategy;
 
@@ -927,7 +935,6 @@
                 fCurrentBRDStrategy++;
             }
             fCurrentBRDStrategy = 0;
-            fCurrentBRDImage++;
         }
 
         return nullptr;