meson: fix build on power/ppc targets with altivec enabled

header_checks/meson.build

@@ -12,6 +12,8 @@ if get_option('native-arch-optimization')
   if cc.has_header(native_header) == false
     error('Error, header '+native_header+' is required')
   endif
+
+  config_h.set10('HAVE_'+native_header.underscorify().to_upper(), true)
 endif
 
 header_checks = [

meson.build

@@ -157,7 +157,7 @@ if get_option('native-arch-optimization')
     message('ARM64 build - NEON + intrinsics enabled')
   elif host_machine.cpu_family() == 'ppc' or host_machine.cpu_family() == 'ppc64'
     config_h.set10('BUILD_ALTIVEC', true)
-    add_global_arguments('-maltivec-vectorize', language: 'c')
+    add_global_arguments('-ftree-vectorize', language: 'c')
     add_global_arguments('-maltivec', language: 'c')
     message('PPC/POWER build - ALTIVEC enabled')
   endif