Simplify the wxWidgets build script

Since we're not using a specific SDK any longer, I cleaned
up the script but still left the ability to specify an SDK
if we need to in the future.

mac/scripts/build_wxwidgets

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 #
 # You can use this to build wxWidgets.  Just run it from within the root of the
 # wxWidgets source tree like so:
@@ -6,87 +6,66 @@
 #  sudo <path to this script>/build_wxwidgets
 #
 
-# Currently, Audacity is built using the 10.9 SDK, but you may choose to target
-# 10.8 or greater by changing this variable.
-min=10.9
+# The minimum OS X version supported by Audacity is 10.7.
+minver=10.7
 
-# You shouldn't need to change this, but just in case you put Xcode in a non-standard
-# location, update this appropriately.
-sdk="/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX${min}.sdk/"
-
-if [ ! -d "${sdk}" ]
-then
-   echo "You must install the ${min} SDK at this location:"
-   echo "${sdk}"
-   exit 1
-fi
-
-max=${min/./}0
-ver="-DMAC_OS_X_VERSION_MAX_ALLOWED=${max} -mmacosx-version-min=${min}"
+# If you want to use a specific SDK, specify the full path here
+sdkdir=""
 
 # Build a specific configuration
 function bld
 {
-   rm -rf "${1}"
-   mkdir -p "${1}"
-   pushd "${1}"
+   flavour="${1}"
    shift
 
-   arch_option="--enable-macosx-arch=${1}"
-   prefix_option="--prefix=/usr/local/${1}"
-   shift
+   # Create and change to our build directory
+   rm -rf "bld_${flavour}_${arch}"
+   mkdir -p "bld_${flavour}_${arch}"
+   pushd "bld_${flavour}_${arch}"
 
-   ../configure ${prefix_option} \
-                ${arch_option} \
-                --with-expat=builtin \
-                --with-zlib=builtin \
-                --with-regex=builtin \
-                --enable-universal_binary=no \
-                --enable-unicode=yes \
-                --enable-webkit=no \
-                --with-macosx-version-min=${min} \
-                ${@}
-   export LDFLAGS="${LDFLAGS1}"
-   xcrun make -j 4
-   export LDFLAGS=""
+   # Force Audacity specific options
+   export CXX="g++ -std=c++1z -stdlib=libc++"
+   export LD="g++ -std=c++1z -stdlib=libc++"
+
+   # Ensure configure uses the proper SDK while performing its tests
+   run="xcrun ${sdkdir:+-sdk ${asdf}}"
+
+   # NOTES: liblzma isn't available on MacOS 10.8 or older and Audacity doesn't
+   #        need it.  So, build wxWidgets without the support to allow Audacity
+   #        to run on MacOS 10.7 or newer.
+   ${run} ../configure --prefix="/usr/local/${arch}" \
+                       --enable-macosx-arch="${arch}" \
+                       --enable-shared=yes \
+                       --enable-unicode=yes \
+                       --enable-universal_binary=no \
+                       --enable-webkit=no \
+                       --with-expat=builtin \
+                       --with-flavour="${flavour}" \
+                       --with-libjpeg=builtin \
+                       --with-libpng=builtin \
+                       --with-libtiff=builtin \
+                       --with-macosx-sdk="${sdkdir}" \
+                       --with-macosx-version-min="${minver}" \
+                       --with-regex=builtin \
+                       --with-zlib=builtin \
+                       --without-liblzma \
+                       ${@}
+   ${run} make -j $(sysctl -n hw.ncpu) install
    popd
 }
 
-# Install a specific configuration
-function inst
-{
-   pushd "${1}"
-   xcrun make install
-   popd
-}
+# If building on 10.15 (Catalina) or newer, 32-bit versions can't be
+# created without forcing "configure" to cross compile.
+arches="x86_64"
+osver=$(sw_vers -productVersion)
+if [ "${osver}" \< "10.15" ]
+then
+   arches="${arches} i386"
+fi
 
-for architecture in 'i386' 'x86_64'; do {
-   std=''
-   stdlib='-stdlib=libstdc++'
-   if [ ${max} -gt 1060 ]
-   then
-      std='-std=c++1z'
-      stdlib='-stdlib=libc++'
-   fi
+for arch in ${arches}
+do
+   bld "debug" --enable-debug=yes
+   bld "release" --enable-debug=no
+done
 
-   arch="-arch ${architecture}"
-   export CPPFLAGS="${ver}"
-   export CFLAGS1="${arch} ${ver} -isysroot $sdk"
-   export CXXFLAGS1="${arch} ${ver} -isysroot $sdk ${std} ${stdlib}"
-   export LDFLAGS1="${arch} ${ver} -syslibroot,$sdk ${std} ${stdlib}"
-
-   # Make sure our flags are included
-   export CC="gcc $CFLAGS1"
-   export CXX="g++ $CXXFLAGS1"
-   export LD="g++ $LDFLAGS1"
-
-   # Build all configurations
-   debug_dir="bld_debug_${architecture}"
-   release_dir="bld_release_${architecture}"
-   bld ${debug_dir} ${architecture} --enable-debug=yes --enable-shared=yes --with-flavour=debug
-   bld ${release_dir} ${architecture} --enable-debug=no --enable-shared=yes --with-flavour=release
-
-   # Install all configurations
-   inst ${debug_dir}
-   inst ${release_dir}
-}; done # loop over architectures