Install ncurses from Homebrew, if available

XCode Command Line Tools 15.0 was recently released, and it contains a
broken version of ncurses 6.0. Some uses of Python's `curses` module
will segfault when compiled with it. The solution is to switch to using
the version of ncurses from Homebrew, which is currently 6.4. Support
for ncurses 6 was added to Python 3.7 and was backported to 3.6 and 2.7,
so this change should not break any recently supported Python versions.

See python/cpython#109617 and
python/cpython#69906 for more information.

plugins/python-build/bin/python-build

@@ -803,6 +803,7 @@ build_package_standard_build() {
     use_homebrew || true
     use_tcltk || true
     use_homebrew_readline || use_freebsd_pkg || true
+    use_homebrew_ncurses || true
     if is_mac -ge 1014; then
       use_xcode_sdk_zlib || use_homebrew_zlib || true
     else
@@ -1468,6 +1469,18 @@ use_homebrew_readline() {
   fi
 }
 
+use_homebrew_ncurses() {
+  can_use_homebrew || return 1
+  local libdir="$(brew --prefix ncurses 2>/dev/null || true)"
+  if [ -d "$libdir" ]; then
+    echo "python-build: use ncurses from homebrew"
+    export CPPFLAGS="-I$libdir/include${CPPFLAGS:+ $CPPFLAGS}"
+    export LDFLAGS="-L$libdir/lib${LDFLAGS:+ $LDFLAGS}"
+  else
+    return 1
+  fi
+}
+
 prefer_openssl11() {
   # Allow overriding the preference of OpenSSL version per definition basis (#1302, #1325, #1326)
   PYTHON_BUILD_HOMEBREW_OPENSSL_FORMULA="${PYTHON_BUILD_HOMEBREW_OPENSSL_FORMULA:-openssl@1.1 openssl}"