gallivm: Allow target specific intrinsics in lp_declare_intrinsic()

Target specific intrinsics are also prefixed with llvm, so this assert
was preventing us from using them.

src/gallium/auxiliary/gallivm/lp_bld_intr.c

@@ -70,13 +70,6 @@ lp_declare_intrinsic(LLVMModuleRef module,
 
    assert(LLVMIsDeclaration(function));
 
-   if(name[0] == 'l' &&
-      name[1] == 'l' &&
-      name[2] == 'v' &&
-      name[3] == 'm' &&
-      name[4] == '.')
-      assert(LLVMGetIntrinsicID(function));
-
    return function;
 }