Don't use String8 path functions

Ideally, we should migrate to std::filesystem, but libc++fs is not
available for vendor binaries until b/175635923 lands.

Bug: 295394788
Test: m checkbuild
Change-Id: If285034d7b343531082d0176ab26bf51390714d0
diff --git a/cas/aidl/default/Android.bp b/cas/aidl/default/Android.bp
index 6ce5681..576016e 100644
--- a/cas/aidl/default/Android.bp
+++ b/cas/aidl/default/Android.bp
@@ -21,6 +21,7 @@
 
     shared_libs: [
         "android.hardware.cas-V1-ndk",
+        "libbase",
         "libbinder_ndk",
         "liblog",
         "libutils",
@@ -48,6 +49,7 @@
     ],
     shared_libs: [
         "android.hardware.cas-V1-ndk",
+        "libbase",
         "libbinder_ndk",
         "liblog",
         "libutils",