Bug 1080342 - Change how the symbols the flash plugin uses are hooked on Android. r=snorp

With bug 1077366, the linker makes the library containing it a fake
LD_PRELOAD. As a consequence, instead of, in the linker itself,
explicitely special-casing the symbols that disappeared in Android 4.4
that the flash plugin uses, it is now possible to use normal symbol
resolution to stubs defined separately in libmozglue.

mozglue/build/BionicGlue.cpp

@@ -260,3 +260,20 @@ extern "C" NS_EXPORT size_t __wrap_strspn(const char * a0, const char * a1) { re
 extern "C" NS_EXPORT int __wrap_strcoll(const char * a0, const char * a1) { return __real_strcoll(a0, a1); }
 extern "C" NS_EXPORT size_t __wrap_strxfrm(char * a0, const char * a1, size_t a2) { return __real_strxfrm(a0, a1, a2); }
 #endif
+
+/* Flash plugin uses symbols that are not present in Android >= 4.4 */
+#ifndef MOZ_WIDGET_GONK
+namespace android {
+  namespace VectorImpl {
+    NS_EXPORT void reservedVectorImpl1(void) { }
+    NS_EXPORT void reservedVectorImpl2(void) { }
+    NS_EXPORT void reservedVectorImpl3(void) { }
+    NS_EXPORT void reservedVectorImpl4(void) { }
+    NS_EXPORT void reservedVectorImpl5(void) { }
+    NS_EXPORT void reservedVectorImpl6(void) { }
+    NS_EXPORT void reservedVectorImpl7(void) { }
+    NS_EXPORT void reservedVectorImpl8(void) { }
+  }
+}
+#endif
+

mozglue/linker/CustomElf.cpp

@@ -74,11 +74,6 @@ static int p_flags_to_mprot(Word flags)
          ((flags & PF_R) ? PROT_READ : 0);
 }
 
-void
-__void_stub(void)
-{
-}
-
 } /* anonymous namespace */
 
 /**
@@ -330,16 +325,6 @@ CustomElf::GetSymbolPtrInDeps(const char *symbol) const
       return FunctionPtr(sigaction);
   }
 
-#define MISSING_FLASH_SYMNAME_START "_ZN7android10VectorImpl19reservedVectorImpl"
-
-  // Android changed some symbols that Flash depended on in 4.4,
-  // so stub those out here
-  if (strncmp(symbol,
-              MISSING_FLASH_SYMNAME_START,
-              sizeof(MISSING_FLASH_SYMNAME_START) - 1) == 0) {
-    return FunctionPtr(__void_stub);
-  }
-
   void *sym;
 
   unsigned long hash = Hash(symbol);