bug 585873 implement RealBreak for arm r=doug a2.0=bsmedberg

xpcom/base/nsDebugImpl.cpp

@@ -393,8 +393,10 @@ RealBreak()
    raise(SIGTRAP);
 #elif defined(__GNUC__) && (defined(__i386__) || defined(__i386) || defined(__x86_64__))
    asm("int $3");
+#elif defined(__arm__)
+   asm("BKPT #0");
 #else
-   // don't know how to break on this platform
+#warning don't know how to break on this platform  
 #endif
 }
 
@@ -493,8 +495,10 @@ Break(const char *aMsg)
    RealBreak();
 #elif defined(__GNUC__) && (defined(__i386__) || defined(__i386) || defined(__x86_64__))
    RealBreak();
+#elif defined(__arm__)
+   RealBreak();
 #else
-   // don't know how to break on this platform
+#warning don't know how to break on this platform
 #endif
 }