gh-38256: `configure`: Check that the build directory is on a normal writable file system
    
<!-- ^ Please provide a concise and informative title. -->
<!-- ^ Don't put issue numbers in the title, do this in the PR
description below. -->
<!-- ^ For example, instead of "Fixes #12345" use "Introduce new method
to calculate 1 + 2". -->
<!-- v Describe your changes below in detail. -->
<!-- v Why is this change required? What problem does it solve? -->
<!-- v If this PR resolves an open issue, please link to it here. For
example, "Fixes #12345". -->

Just another protection for users who skip reading the README

Fixes #38246

### 📝 Checklist

<!-- Put an `x` in all the boxes that apply. -->

- [x] The title is concise and informative.
- [ ] The description explains in detail what this PR is about.
- [x] I have linked a relevant issue or discussion.
- [ ] I have created tests covering the changes.
- [ ] I have updated the documentation and checked the documentation
preview.

### ⌛ Dependencies

<!-- List all open PRs that this PR logically depends on. For example,
-->
<!-- - #12345: short description why this is a dependency -->
<!-- - #34567: ... -->
    
URL: #38256
Reported by: Matthias Köppe
Reviewer(s): Sébastien Labbé

Author: Release Manager

configure.ac

@@ -537,6 +537,19 @@ AC_CONFIG_COMMANDS(mkdirs,
             AC_MSG_NOTICE([[creating symbolic link lib64 -> lib]])
             ln -s lib "$SAGE_LOCAL/lib64"
         fi
+        dnl Check that the file system is sufficiently functional
+        if test -z "$SAGE_BUILD_DIR"; then
+            SAGE_BUILD_DIR="$SAGE_LOCAL/var/tmp/sage/build"
+        fi
+        AC_MSG_NOTICE([creating directory $SAGE_BUILD_DIR])
+        mkdir -p "$SAGE_BUILD_DIR" || AC_MSG_ERROR([error creating directory $SAGE_BUILD_DIR (SAGE_BUILD_DIR)])
+        rm -f "$SAGE_BUILD_DIR"/conftest
+        touch "$SAGE_BUILD_DIR"/conftest || AC_MSG_ERROR([error creating a file in $SAGE_BUILD_DIR])
+        chmod +x "$SAGE_BUILD_DIR"/conftest || AC_MSG_ERROR([error setting file permissions +x in $SAGE_BUILD_DIR])
+        test -x "$SAGE_BUILD_DIR"/conftest || AC_MSG_ERROR([file permissions +x did not persist in $SAGE_BUILD_DIR])
+        chmod -x "$SAGE_BUILD_DIR"/conftest || AC_MSG_ERROR([error setting file permissions -x in $SAGE_BUILD_DIR])
+        test -x "$SAGE_BUILD_DIR"/conftest && AC_MSG_ERROR([file permissions -x did not persist in $SAGE_BUILD_DIR])
+        rm -f "$SAGE_BUILD_DIR"/conftest
     ],
     [
         SAGE_LOGS="$SAGE_ROOT/logs/pkgs"