userdiff-cpp: prepare test cases with yet unsupported features

We are going to add support for C++'s digit-separating single-quote and
the spaceship operator. By adding the test cases in this separate
commit, the effect on the word highlighting will become more obvious
as the features are implemented and the file cpp/expect is updated.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t4034/cpp/post

@@ -1,16 +1,16 @@
 Foo() : x(0&42) { bar(x.Find); }
 cout<<"Hello World?\n"<<endl;
-(1 +1e10 0xabcdef) 'y'
+(1 +1e10 0xabcdef) '.'
 // long double
-3.141592654e+10l
+3.141'592'654e+10l
 // float
 120E6f
 // hex
-0xdeadBeaf+7ULL
+0xdead'Beaf+7ULL
 // octal
-01234560
+0123'4560
 // binary
-0b1100+e1
+0b11'00+e1
 // expression
 1.5-e+3+f
 // another one
@@ -20,7 +20,7 @@ str.e+75
 a*=b c/=d e%=f
 a++b c--d
 a<<=b c>>=d
-a<=b c<d e>=f g>h
+a<=b c<d e>=f g>h i<=>j
 a!=b c=d
 a^=b c|=d e&=f
 a|b