Fix clang-tidy warnings in aapt and aapt2.

* Add explicit keyword to conversion constructors.
* Add NOLINT(implicit) comments for implicit conversion constructors.
Bug: 28341362
* Use const reference type for read-only parameters.
Bug: 30407689
* Use const reference type to avoid unnecessary copy.
Bug: 30413862
Test: build with WITH_TIDY=1

Change-Id: Id6d21961f313a1ad92b15a37fdaa5be9e8ab48e1
diff --git a/tools/aapt/ResourceTable.cpp b/tools/aapt/ResourceTable.cpp
index 4d5bb31..76c59dd 100644
--- a/tools/aapt/ResourceTable.cpp
+++ b/tools/aapt/ResourceTable.cpp
@@ -4081,7 +4081,7 @@
     
     j = 0;
     for (i=0; i<N; i++) {
-        sp<ConfigList> e = origOrder.itemAt(i);
+        const sp<ConfigList>& e = origOrder.itemAt(i);
         // There will always be enough room for the remaining entries.
         while (mOrderedConfigs.itemAt(j) != NULL) {
             j++;
@@ -4203,7 +4203,7 @@
 
     size_t j=0;
     for (i=0; i<N; i++) {
-        sp<Type> t = origOrder.itemAt(i);
+        const sp<Type>& t = origOrder.itemAt(i);
         // There will always be enough room for the remaining types.
         while (mOrderedTypes.itemAt(j) != NULL) {
             j++;
@@ -4636,7 +4636,7 @@
                         c->getEntries();
                 const size_t entryCount = entries.size();
                 for (size_t ei = 0; ei < entryCount; ei++) {
-                    sp<Entry> e = entries.valueAt(ei);
+                    const sp<Entry>& e = entries.valueAt(ei);
                     if (e == NULL || e->getType() != Entry::TYPE_BAG) {
                         continue;
                     }