Migrate from android::String isEmpty to empty [aapt]

This empty method is different from the old one - it aligns with
std::string definition.

Bug: 295394788
Test: make checkbuild
Change-Id: I1900f2285ee3c3b1eb57d2cef3990896a64dae01
Merged-In: I1900f2285ee3c3b1eb57d2cef3990896a64dae01
diff --git a/tools/split-select/SplitDescription.cpp b/tools/split-select/SplitDescription.cpp
index 4e2b48e..7150008 100644
--- a/tools/split-select/SplitDescription.cpp
+++ b/tools/split-select/SplitDescription.cpp
@@ -70,7 +70,7 @@
 String8 SplitDescription::toString() const {
     String8 extension;
     if (abi != abi::Variant_none) {
-        if (extension.isEmpty()) {
+        if (extension.empty()) {
             extension.append(":");
         } else {
             extension.append("-");