AAPT: Ignore densities specified in -c flag

The --preferred-density flag knows how to handle missing resources of
specific densities. Using -c with a density leads to missing resources.

Change-Id: I2251d842f48c08ed083663bb7ed608e14c4983c8

tools/aapt/ResourceFilter.cpp

@@ -41,6 +41,13 @@ WeakResourceFilter::parse(const String8& str)
         // Ignore the version
         entry.second &= ~ResTable_config::CONFIG_VERSION;
 
+        // Ignore any densities. Those are best handled in --preferred-density
+        if ((entry.second & ResTable_config::CONFIG_DENSITY) != 0) {
+            fprintf(stderr, "warning: ignoring flag -c %s. Use --preferred-density instead.\n", entry.first.toString().string());
+            entry.first.density = 0;
+            entry.second &= ~ResTable_config::CONFIG_DENSITY;
+        }
+
         mConfigMask |= entry.second;
     }