Trac #33243: Parallel docbuild broken with GNU make 4

This affects all current Linux distros. Broken by #33130. (It works fine
on GNU make 3, the version provided by Xcode on macOS.)

Reported in https://groups.google.com/g/sage-
devel/c/jxIjXoXL5FU/m/nu8xp06jBwAJ

URL: https://trac.sagemath.org/33243
Reported by: mkoeppe
Ticket author(s): Matthias Koeppe
Reviewer(s): Markus Wageringel

Author: Release Manager

.github/workflows/ticket.yaml

@@ -0,0 +1,31 @@
+# CI Test For Individual Tickets
+
+name: Ticket CI
+
+on:
+  push:
+    branches:
+      # Once set to positive review, the branch from the trac ticket
+      # number 12345 will be copied to ticket/12345
+      - 'ticket/**'
+
+
+jobs:
+  ticket_ci:
+
+    # TODO: this action is only a placeholder, github actions needs
+    # this in the master branch to enable it
+
+    name: Ticket CI
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v2
+    - name: Set up Python
+      uses: actions/setup-python@v2
+      with:
+        python-version: 3.8
+    - name: Install pycodestyle
+      run: pip install tox pycodestyle
+    - name: Lint using pycodestyle
+      run: tox -e pycodestyle-minimal

build/make/Makefile.in

@@ -184,7 +184,7 @@ AM_V_at =
 endif
 
 # Trac #33125: Handle make options -n, -t, -q
-ifeq ($(foreach flag, n t q, $(findstring $(flag),$(filter-out --%,$(MAKEFLAGS)))),)
+ifeq ($(strip $(foreach flag,n t q,$(findstring $(flag),$(filter-out --%,$(MAKEFLAGS))))),)
 PLUS = +
 else
 PLUS =

build/pkgs/configure/checksums.ini

@@ -1,4 +1,4 @@
 tarball=configure-VERSION.tar.gz
-sha1=61c83da0394100f82ff51a264c8defd34d2fee84
-md5=a3e9266838a69d32fb80ead2c3b2ffc7
-cksum=3510162262
+sha1=8209739ce4ad39a2db92d869bb409249937ea542
+md5=b17ec372ea4b3cbcd467caa1986c1424
+cksum=70978832

build/pkgs/configure/package-version.txt

@@ -1 +1 @@
-10b4d19e542426bac8e49aca532af32f0bf1eace
+86ce7ada38fd23f805c2571cdafa21d1240b3075