stdenv: `runPhase` returns status (#330751)

pkgs/stdenv/generic/setup.sh

···
 
 
 runPhase() {
+    local retval=0
     local curPhase="$*"
     if [[ "$curPhase" = unpackPhase && -n "${dontUnpack:-}" ]]; then return; fi
     if [[ "$curPhase" = patchPhase && -n "${dontPatch:-}" ]]; then return; fi
···
     startTime=$(date +"%s")
 
     # Evaluate the variable named $curPhase if it exists, otherwise the
-    # function named $curPhase.
-    eval "${!curPhase:-$curPhase}"
+    # function named $curPhase. Trap errors in subshell to set non-zero retval.
+    trap 'retval=1; trap - ERR' ERR
+    eval "set -o errtrace; ${!curPhase:-$curPhase}"
 
     endTime=$(date +"%s")
 
···
 
         cd -- "${sourceRoot:-.}"
     fi
+
+    return $retval
 }