macports.tcl: fix build_arch choice for ppc

Author: barracuda156

src/macports1.0/macports.tcl

@@ -1503,7 +1503,9 @@ match macports.conf.default."
     # Default arch to build for
     if {![info exists build_arch]} {
         if {$os_platform eq "darwin"} {
-            if {$os_major >= 20} {
+            if {$os_arch eq "powerpc"} {
+                set build_arch ppc
+            } elseif {$os_major >= 20} {
                 if {$os_arch eq "arm"} {
                     set build_arch arm64
                 } else {
@@ -1516,11 +1518,7 @@ match macports.conf.default."
                     set build_arch i386
                 }
             } else {
-                if {$os_arch eq "powerpc"} {
-                    set build_arch ppc
-                } else {
-                    set build_arch i386
-                }
+                set build_arch i386
             }
         } else {
             switch -glob $tcl_platform(machine) {