gh-37914: `build/pkgs/python3`: Update to 3.11.8, remove Cygwin patches, remove pointless rpaths on macOS
    
<!-- ^ 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". -->

Author: @culler

Split out from:
- #37886

### 📝 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: #37914
Reported by: Matthias Köppe
Reviewer(s):

Author: Release Manager

build/pkgs/python3/checksums.ini

@@ -1,5 +1,5 @@
 tarball=Python-VERSION.tar.xz
-sha1=89ee31611b73dc0c32c178d15aa208734b462c5a
-md5=4efe92adf28875c77d3b9b2e8d3bc44a
-cksum=2916176597
+sha1=a368aeed7a3325e47b55168452c356a8eb27ab50
+md5=b353b8433e560e1af2b130f56dfbd973
+cksum=534846730
 upstream_url=https://www.python.org/ftp/python/VERSION/Python-VERSION.tar.xz

build/pkgs/python3/package-version.txt

@@ -1 +1 @@
-3.11.1
+3.11.8

build/pkgs/python3/patches/2.6.5-FD_SETSIZE.patch

@@ -73,25 +73,26 @@ sdh_configure --enable-shared $PYTHON_CONFIGURE
 # we need to provide paths into $SAGE_LOCAL, so that setup.py finds
 # the libraries needed for the extension modules - in particular sqlite3.
 # (The search code there does not know about CPATH and LIBRARY_PATH.)
-make_LDFLAGS="-L. -Wl,-rpath,. -L$SAGE_LOCAL/lib $LDFLAGS"
-make_CPPFLAGS="-I$SAGE_LOCAL/include $CPPFLAGS"
 
-# Also, we need to add an rpath, like we do for SAGE_LOCAL in src/bin/sage-env.
-# SAGE_INST_LOCAL is the installation hierarchy for the current package
-# -- for python3, this is SAGE_VENV.
-make_LDFLAGS="-Wl,-rpath,$SAGE_INST_LOCAL/lib $make_LDFLAGS"
+if [ "$UNAME" = "Darwin" ]; then
+    make_LDFLAGS="-L$SAGE_LOCAL/lib -L$SAGE_INST_LOCAL/lib $LDFLAGS"
+    # This enables python to find libpython
+    export DYLD_LIBRARY_PATH="."
+fi
 if [ "$UNAME" = "Linux" ]; then
+    make_LDFLAGS="-L. -Wl,-rpath,. -L$SAGE_LOCAL/lib $LDFLAGS"
+    make_CPPFLAGS="-I$SAGE_LOCAL/include $CPPFLAGS"
+    # Also, we need to add an rpath, like we do for SAGE_LOCAL in src/bin/sage-env.
+    # SAGE_INST_LOCAL is the installation hierarchy for the current package
+    # -- for python3, this is SAGE_VENV.
+    make_LDFLAGS="-Wl,-rpath,$SAGE_INST_LOCAL/lib $make_LDFLAGS"
     make_LDFLAGS="-Wl,-rpath-link,$SAGE_INST_LOCAL/lib $make_LDFLAGS"
+    # This enables python to find libpython
+    export LD_LIBRARY_PATH="."
 fi
 
 sdh_make LDFLAGS="$make_LDFLAGS" CPPFLAGS="$make_CPPFLAGS"
 
-if [ "$UNAME" = "Darwin" ]; then
-    export DYLD_LIBRARY_PATH="."
-else
-    export LD_LIBRARY_PATH="."
-fi
-
 # When building on a case-insensitive filesystem (on any OS, not just Windows)
 # the Python executable is output to the build directory as 'python.exe'
 if [ -f "python.exe" ]; then