wafHook: run waf without explicit python interpreter (#396641)

pkgs/by-name/wa/waf/setup-hook.sh

···
 wafConfigurePhase() {
     runHook preConfigure
 
-    if ! [ -f "${wafPath:=./waf}" ]; then
+    if [ -f "${wafPath:=./waf}" ]; then
+        patchShebangs --build "${wafPath}"
+    else
         wafPath="@waf@/bin/waf"
     fi
 
···
     concatTo flagsArray wafConfigureFlags wafConfigureFlagsArray wafConfigureTargets=configure
 
     echoCmd 'waf configure flags' "${flagsArray[@]}"
-    python "$wafPath" "${flagsArray[@]}"
+    "$wafPath" "${flagsArray[@]}"
 
     if ! [[ -v enableParallelBuilding ]]; then
         enableParallelBuilding=1
···
     concatTo flagsArray wafFlags wafFlagsArray wafBuildFlags wafBuildFlagsArray wafBuildTargets=build
 
     echoCmd 'waf build flags' "${flagsArray[@]}"
-    python "$wafPath" "${flagsArray[@]}"
+    "$wafPath" "${flagsArray[@]}"
 
     runHook postBuild
 }
···
     concatTo flagsArray wafFlags wafFlagsArray wafInstallFlags wafInstallFlagsArray wafInstallTargets=install
 
     echoCmd 'waf install flags' "${flagsArray[@]}"
-    python "$wafPath" "${flagsArray[@]}"
+    "$wafPath" "${flagsArray[@]}"
 
     runHook postInstall
 }