Throw IOException at source of failing to open a dex file.

Before is:
java.lang.ClassNotFoundException: Didn't find class "GCBench" on path: DexPathList[[zip file "/disk2/dalvik-dev/out/host/linux-x86/framework/GCBench.jar"],nativeLibraryDirectories=[/disk2/dalvik-dev/out/host/linux-x86/lib]]
        at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:469)
        Suppressed: java.lang.ClassNotFoundException: GCBench
                at java.lang.Class.classForName(Native Method)
                at java.lang.BootClassLoader.findClass(ClassLoader.java:781)
                at java.lang.BootClassLoader.loadClass(ClassLoader.java:841)
                at java.lang.ClassLoader.loadClass(ClassLoader.java:504)
                ... 1 more
        Caused by: java.lang.NoClassDefFoundError: Class "LGCBench;" not found
                ... 5 more
And after is:
java.lang.ClassNotFoundException: Didn't find class "GCBench" on path: DexPathList[[zip file "/disk2/dalvik-dev/out/host/linux-x86/framework/GCBench.jar"],nativeLibraryDirectories=[/disk2/dalvik-dev/out/host/linux-x86/lib]]
        at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:469)
        Suppressed: java.io.IOException: Zip archive '/disk2/dalvik-dev/out/host/linux-x86/framework/GCBench.jar' doesn't contain classes.dex
                at dalvik.system.DexFile.openDexFile(Native Method)
                at dalvik.system.DexFile.<init>(DexFile.java:80)
                at dalvik.system.DexFile.<init>(DexFile.java:59)
                at dalvik.system.DexPathList.loadDexFile(DexPathList.java:268)
                at dalvik.system.DexPathList.makeDexElements(DexPathList.java:235)
                at dalvik.system.DexPathList.<init>(DexPathList.java:113)
                at dalvik.system.BaseDexClassLoader.<init>(BaseDexClassLoader.java:48)
                at dalvik.system.PathClassLoader.<init>(PathClassLoader.java:38)
                at java.lang.ClassLoader.createSystemClassLoader(ClassLoader.java:128)
                at java.lang.ClassLoader.access$000(ClassLoader.java:65)
                at java.lang.ClassLoader$SystemClassLoader.<clinit>(ClassLoader.java:81)
                at java.lang.ClassLoader.getSystemClassLoader(ClassLoader.java:137)
        Suppressed: java.lang.ClassNotFoundException: GCBench
                at java.lang.Class.classForName(Native Method)
                at java.lang.BootClassLoader.findClass(ClassLoader.java:781)
                at java.lang.BootClassLoader.loadClass(ClassLoader.java:841)
                at java.lang.ClassLoader.loadClass(ClassLoader.java:504)
                ... 1 more
        Caused by: java.lang.NoClassDefFoundError: Class "LGCBench;" not found
                ... 5 more

Also, move dex file verifier messages out of logs.
In the process the ClassLinker::dex_lock_ needed tidying to cover a smaller
scope. Bug 11301553.

Change-Id: I80058652e11e7ea63457cc01a0cb48afe1c15543
diff --git a/runtime/gc/space/image_space.h b/runtime/gc/space/image_space.h
index 381a98e..78a83c9 100644
--- a/runtime/gc/space/image_space.h
+++ b/runtime/gc/space/image_space.h
@@ -45,12 +45,11 @@
   // creation of the alloc space. The ReleaseOatFile will later be
   // used to transfer ownership of the OatFile to the ClassLinker when
   // it is initialized.
-  static ImageSpace* Create(const std::string& image)
-      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
+  static ImageSpace* Create(const char* image) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
   // Releases the OatFile from the ImageSpace so it can be transfer to
   // the caller, presumably the ClassLinker.
-  OatFile& ReleaseOatFile()
+  OatFile* ReleaseOatFile()
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
   void VerifyImageAllocations()
@@ -84,13 +83,13 @@
   // image's OatFile is up-to-date relative to its DexFile
   // inputs. Otherwise (for /data), validate the inputs and generate
   // the OatFile in /data/dalvik-cache if necessary.
-  static ImageSpace* Init(const std::string& image, bool validate_oat_file)
+  static ImageSpace* Init(const char* image, bool validate_oat_file, std::string* error_msg)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
-  OatFile* OpenOatFile() const
+  OatFile* OpenOatFile(std::string* error_msg) const
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
-  bool ValidateOatFile() const
+  bool ValidateOatFile(std::string* error_msg) const
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
   friend class Space;