stagefright-plugins: Fix crash during testDecodeWithEOSOnLastBuffer
stagefright-plugins: Fix crash during testDecodeWithEOSOnLastBuffer

 * Don't blindly dequeue a buffer, it could be garbage in which case
   we just crash and fail CTS :(

Change-Id: I6541b75890da8d9e55d5bf0b2126cea2688febba

AOSPB/external_stagefright-plugins,PAC-ROM/android_external_stagefright-plugins,Evervolv/android_external_stagefright-plugins,DirtyUnicorns/android_external_stagefright-plugins,TeamExodus/external_stagefright-plugins,SlimRoms/android_external_stagefright-plugins,AOSPB/external_stagefright-plugins,SlimRoms/android_external_stagefright-plugins,PAC-ROM/android_external_stagefright-plugins,TeamExodus/external_stagefright-plugins,AOSP-CAF/platform_external_stagefright-plugins,BrokenROM/external_stagefright-plugins,Evervolv/android_external_stagefright-plugins,AOSP-CAF/platform_external_stagefright-plugins,DirtyUnicorns/android_external_stagefright-plugins,VRToxin/android_external_stagefright-plugins,VRToxin/android_external_stagefright-plugins,BrokenROM/external_stagefright-plugins