This adds the following signatures into altivec.h:
vector bool long long vec_mergee (vector bool long long, vector bool long long);
vector signed long long vec_mergee (vector signed long long, vector signed long long);
vector unsigned long long vec_mergee (vector unsigned long long, vector unsigned long long);
vector float vec_mergee (vector float, vector float);
vector double vec_mergee (vector double, vector double);
vector bool long long vec_mergeo (vector bool long long, vector bool long long);
vector signed long long vec_mergeo (vector signed long long, vector signed long long);
vector unsigned long long vec_mergeo (vector unsigned long long, vector unsigned long long);
vector double vec_mergeo (vector double, vector double);
vector float vec_mergeo (vector float, vector float);
vector unsigned short vec_pack_to_short_fp32 (vector float, vector float);
vector bool char vec_permxor (vector bool char, vector bool char, vector bool char);
vector unsigned char vec_permxor (vector signed char, vector signed char, vector signed char);
vector unsigned char vec_permxor (vector unsigned char, vector unsigned char, vector unsigned char);
vector unsigned int vec_rlmi (vector unsigned int, vector unsigned int, vector unsigned int);
vector unsigned long long vec_rlmi (vector unsigned long long, vector unsigned long long, vector unsigned long long);
vector unsigned int vec_rlnm (vector unsigned int, vector unsigned int, vector unsigned int);
vector double vec_unpackh (vector float);
vector double vec_unpackl (vector float);
vector float vec_pack (vector double, vector double);
A minor quibble: we have the __builtin_altivec_* functions added after the vsx builtins, rather than with the rest of the altivec builtins.