Update libmagic.patch

Some commits missed to update the patch file, so we're catching up on
this.

To generally make this easier, we back-port generate_patch.sh from
PHP-7.4, where we now also generate magic.h from magic.h.in.

Author: cmb69

ext/fileinfo/generate_patch.sh

@@ -0,0 +1,8 @@
+VERSION=5.33
+if [[ ! -d libmagic.orig ]]; then
+  mkdir libmagic.orig
+  wget -O - ftp://ftp.astron.com/pub/file/file-$VERSION.tar.gz \
+    | tar -xz --strip-components=2 -C libmagic.orig file-$VERSION/src
+fi
+sed -e "s/X\.YY/${VERSION//.}/g" libmagic.orig/magic.h.in > libmagic.orig/magic.h
+diff -u libmagic.orig libmagic | grep -v '^Only in' > libmagic.patch