LibC: Replace use of do/while in assert() with the ternary operator

It's a single expression, no do/while needed. This makes assert() work
with the comma operator (assert(foo), assert(bar), assert(baz)).
Found because exactly this is being used somewhere in the guts of LLVM.

Userland/Libraries/LibC/assert.h

@@ -14,11 +14,11 @@ __BEGIN_DECLS
 __attribute__((noreturn)) void __assertion_failed(const char* msg);
 # define __stringify_helper(x) # x
 # define __stringify(x) __stringify_helper(x)
-# define assert(expr) \
- do {  \
- if (__builtin_expect(!(expr), 0))  \
- __assertion_failed(#expr "\n" __FILE__ ":" __stringify(__LINE__)); \
- } while (0)
+# define assert(expr)  \
+ (__builtin_expect(!(expr), 0) \
+  ? __assertion_failed(#expr "\n" __FILE__ ":" __stringify(__LINE__)) \
+ : void(0))
+
 #else
 # define assert(expr) ((void)(0))
 # define VERIFY_NOT_REACHED() _abort()