proguard: cleanup unused parts

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

ui/build.gradle

@@ -34,7 +34,7 @@ android {
         release {
             minifyEnabled true
             shrinkResources true
-            proguardFiles "proguard-android-optimize.txt", "proguard-rules.pro"
+            proguardFiles "proguard-android-optimize.txt"
             packagingOptions {
                 exclude "DebugProbesKt.bin"
                 exclude "kotlin-tooling-metadata.json"

ui/proguard-android-optimize.txt

@@ -1,7 +1,6 @@
 -allowaccessmodification
--dontpreverify
 -dontusemixedcaseclassnames
--dontskipnonpubliclibraryclasses
+-dontobfuscate
 -verbose
 
 -keepattributes *Annotation*

ui/proguard-rules.pro

@@ -1,14 +0,0 @@
-# Squelch all warnings, they're harmless but ProGuard
-# escalates them as errors.
--dontwarn sun.misc.Unsafe
-
-# Fragment 1.2.4 allows Fragment classes to be obfuscated but
-# databinding references in XML seem to not be rewritten to
-# match, so we preserve the names as 1.2.3 did.
--if public class ** extends androidx.fragment.app.Fragment
--keep public class <1> {
-    public <init>();
-}
-
-# Don't obfuscate
--dontobfuscate