oops, wrong dependency in bison rules

dtool/pptempl/Template.gmsvc.pp

@@ -759,6 +759,7 @@ $[TAB] cp $[target_header] $[target_header].prebuilt
 #define source $[target].prebuilt
 $[target] : $[source]
 $[TAB] cp $[source] $[target]
+#define source $[target_header].prebuilt
 $[target_header] : $[source]
 $[TAB] cp $[source] $[target_header]
 #endif // HAVE_BISON

dtool/pptempl/Template.msvc.pp

@@ -733,6 +733,7 @@ $[TAB] copy $[target_header] $[target_header].prebuilt
 #define source $[target].prebuilt
 $[target] : $[source]
 $[TAB] copy $[source] $[target]
+#define source $[target_header].prebuilt
 $[target_header] : $[source]
 $[TAB] copy $[source] $[target_header]
 #endif // HAVE_BISON

dtool/pptempl/Template.unix.pp

@@ -608,6 +608,7 @@ $[TAB]cp $[target_header] $[target_header].prebuilt
 #define source $[target].prebuilt
 $[target] : $[source]
 $[TAB]cp $[source] $[target]
+#define source $[target_header].prebuilt
 $[target_header] : $[source]
 $[TAB]cp $[source] $[target_header]
 #endif // HAVE_BISON