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/compiler/elf_writer_test.cc b/compiler/elf_writer_test.cc
index ffe1f72..eca67a8 100644
--- a/compiler/elf_writer_test.cc
+++ b/compiler/elf_writer_test.cc
@@ -65,23 +65,26 @@
   UniquePtr<File> file(OS::OpenFileForReading(elf_filename.c_str()));
   ASSERT_TRUE(file.get() != NULL);
   {
-    UniquePtr<ElfFile> ef(ElfFile::Open(file.get(), false, false));
-    CHECK(ef.get() != NULL);
+    std::string error_msg;
+    UniquePtr<ElfFile> ef(ElfFile::Open(file.get(), false, false, &error_msg));
+    CHECK(ef.get() != nullptr) << error_msg;
     EXPECT_ELF_FILE_ADDRESS(ef, dl_oatdata, "oatdata", false);
     EXPECT_ELF_FILE_ADDRESS(ef, dl_oatexec, "oatexec", false);
     EXPECT_ELF_FILE_ADDRESS(ef, dl_oatlastword, "oatlastword", false);
   }
   {
-    UniquePtr<ElfFile> ef(ElfFile::Open(file.get(), false, false));
-    CHECK(ef.get() != NULL);
+    std::string error_msg;
+    UniquePtr<ElfFile> ef(ElfFile::Open(file.get(), false, false, &error_msg));
+    CHECK(ef.get() != nullptr) << error_msg;
     EXPECT_ELF_FILE_ADDRESS(ef, dl_oatdata, "oatdata", true);
     EXPECT_ELF_FILE_ADDRESS(ef, dl_oatexec, "oatexec", true);
     EXPECT_ELF_FILE_ADDRESS(ef, dl_oatlastword, "oatlastword", true);
   }
   {
-    UniquePtr<ElfFile> ef(ElfFile::Open(file.get(), false, true));
-    CHECK(ef.get() != NULL);
-    ef->Load(false);
+    std::string error_msg;
+    UniquePtr<ElfFile> ef(ElfFile::Open(file.get(), false, true, &error_msg));
+    CHECK(ef.get() != nullptr) << error_msg;
+    CHECK(ef->Load(false, &error_msg)) << error_msg;
     EXPECT_EQ(dl_oatdata, ef->FindDynamicSymbolAddress("oatdata"));
     EXPECT_EQ(dl_oatexec, ef->FindDynamicSymbolAddress("oatexec"));
     EXPECT_EQ(dl_oatlastword, ef->FindDynamicSymbolAddress("oatlastword"));