graphics/mesa-dri: fix build on powerpc64le

n file included from ../src/gallium/drivers/llvmpipe/lp_setup_tri.c:50:
/usr/lib/clang/11.0.1/include/altivec.h:55:19: error: unknown type name 'vector'
static inline vector bool char __ATTRS_o_ai

^

/usr/lib/clang/11.0.1/include/altivec.h:56:10: error: unknown type name 'vector'
vec_perm(vector bool char a, vector bool char b, vector unsigned char __c);

^

/usr/lib/clang/11.0.1/include/altivec.h:56:32: error: unknown type name 'vector'
vec_perm(vector bool char a, vector bool char b, vector unsigned char __c);

^

/usr/lib/clang/11.0.1/include/altivec.h:66:19: error: unknown type name 'vector'
static inline vector bool short __ATTRS_o_ai vec_perm(

^

/usr/lib/clang/11.0.1/include/altivec.h:67:5: error: unknown type name 'vector'

vector bool short __a, vector bool short __b, vector unsigned char __c);
^

/usr/lib/clang/11.0.1/include/altivec.h:67:28: error: unknown type name 'vector'

vector bool short __a, vector bool short __b, vector unsigned char __c);
                       ^

/usr/lib/clang/11.0.1/include/altivec.h:80:19: error: unknown type name 'vector'
static inline vector bool int __ATTRS_o_ai

^

/usr/lib/clang/11.0.1/include/altivec.h:81:10: error: unknown type name 'vector'
vec_perm(vector bool int a, vector bool int b, vector unsigned char __c);

^

/usr/lib/clang/11.0.1/include/altivec.h:81:31: error: unknown type name 'vector'
vec_perm(vector bool int a, vector bool int b, vector unsigned char __c);

^

/usr/lib/clang/11.0.1/include/altivec.h:96:19: error: unknown type name 'vector'
static inline vector bool long long __ATTRS_o_ai

^

/usr/lib/clang/11.0.1/include/altivec.h:97:10: error: unknown type name 'vector'
vec_perm(vector bool long long a, vector bool long long b,

^

/usr/lib/clang/11.0.1/include/altivec.h:97:37: error: unknown type name 'vector'
vec_perm(vector bool long long a, vector bool long long b,

^

/usr/lib/clang/11.0.1/include/altivec.h:203:9: error: unknown type name 'vector'
vec_add(vector bool char a, vector signed char b) {

^

/usr/lib/clang/11.0.1/include/altivec.h:208:33: error: unknown type name 'vector'
vec_add(vector signed char a, vector bool char b) {

^

/usr/lib/clang/11.0.1/include/altivec.h:218:9: error: unknown type name 'vector'
vec_add(vector bool char a, vector unsigned char b) {

^

/usr/lib/clang/11.0.1/include/altivec.h:223:35: error: unknown type name 'vector'
vec_add(vector unsigned char a, vector bool char b) {

^

/usr/lib/clang/11.0.1/include/altivec.h:232:53: error: unknown type name 'vector'
static inline vector short ATTRS_o_ai vec_add(vector bool short a,

^

/usr/lib/clang/11.0.1/include/altivec.h:238:53: error: unknown type name 'vector'

vector bool short __b) {
^

/usr/lib/clang/11.0.1/include/altivec.h:248:9: error: unknown type name 'vector'
vec_add(vector bool short a, vector unsigned short b) {

^

fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.

Additionally, fix packaging failure on all powerpc*, since llvmpipe is now used.