opt/telephony: Fix compile on JDK7

UNEXPECTED TOP-LEVEL EXCEPTION:
com.android.dx.util.ExceptionWithContext
        at
com.android.dx.util.ExceptionWithContext.withContext(ExceptionWithContext.java:46)
        at com.android.dx.dex.cf.CfTranslator.processMethods(CfTranslator.java:344)
        at com.android.dx.dex.cf.CfTranslator.translate0(CfTranslator.java:134)
        at com.android.dx.dex.cf.CfTranslator.translate(CfTranslator.java:87)
        at com.android.dx.command.dexer.Main.processClass(Main.java:487)
        at com.android.dx.command.dexer.Main.processFileBytes(Main.java:459)
        at com.android.dx.command.dexer.Main.access$400(Main.java:67)
        at com.android.dx.command.dexer.Main$1.processFileBytes(Main.java:398)
        at com.android.dx.cf.direct.ClassPathOpener.processArchive(ClassPathOpener.java:245)
        at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:131)
        at com.android.dx.cf.direct.ClassPathOpener.process(ClassPathOpener.java:109)
        at com.android.dx.command.dexer.Main.processOne(Main.java:422)
        at com.android.dx.command.dexer.Main.processAllFiles(Main.java:333)
        at com.android.dx.command.dexer.Main.run(Main.java:209)
        at com.android.dx.command.dexer.Main.main(Main.java:174)
        at com.android.dx.command.Main.main(Main.java:91)
Caused by: java.lang.NullPointerException
        at com.android.dx.cf.code.ConcreteMethod.<init>(ConcreteMethod.java:87)
        at com.android.dx.cf.code.ConcreteMethod.<init>(ConcreteMethod.java:75)
        at com.android.dx.dex.cf.CfTranslator.processMethods(CfTranslator.java:247)
        ... 14 more
...while processing <init> (Lcom/android/internal/telephony/gsm/GSMPhone;)V
...while processing com/android/internal/telephony/gsm/GSMPhone$1.class

Change-Id: If39b2067c9190f0f3ed6cd3bb909ccc3201262cb