Write tests for new APE loader and fix bugs

- Add FreeBSD-specific mmap() flags
- Reduce size of the APE loader from 8kb to 4kb
- Work towards fixing the Makefile build on WSL
- Automate testing of APE no-modify-self behaviors
- Make the ape.S shell script code cleaner and tinier
- Improve the APE sanity check to test behavior better
- Fixed issue with ShowCrashReports() sigaltstack() on BSDs
- Delete symbols for S_MODE magnums which wasted compile time

If you checked out yesterday's APE commit, please run:

    rm -f /usr/bin/ape o/tmp/ape /tmp/ape "${TMPDIR:-/tmp}/ape"

Because this change fixes certain aspects of the new ABI. We don't have
automated migrations for APE loader versions yet. Thanks! You can also
download prebuilt binaries here:

- https://justine.lol/ape.elf    (Linux/FreeBSD/NetBSD/OpenBSD)
- https://justine.lol/ape.macho  (Apple)

Install the appropriate one as `/usr/bin/ape`.

build/sanitycheck

@@ -27,28 +27,38 @@ EOF
   exit 1
 fi
 
-build/sanitycheck2
-if [ $? -ne 123 ]; then
+if [ ! -f /proc/sys/fs/binfmt_misc/status ]; then
+  exit 0
+fi
+
+STATUS="$(build/bootstrap/apetest.com)"
+if [ x"$STATUS" != xsuccess ]; then
   cat <<'EOF' >&2
 
 ERROR
 
-  Thompson Shell Backwards Compatibility Issue Detected
+  APE Execution error.
 
 DETAILS
 
-  Your system has likely been configured to use binfmt_misc and wine.
-  You need to run the command below which will install a /usr/bin/ape
-  program and then register it with binfmt_misc. See ape/loader.c for
-  source code and technical details.
+  Your system has probably been configured to use binfmt_misc. You need
+  to run the command below to install /usr/bin/ape and register it with
+  binfmt_misc. See ape/loader.c for source code, and technical details.
 
 WORKAROUND
 
   ape/apeinstall.sh
 
+NOTES
+
+  If it still doesn't work, possibly due to an overly aggressive WINE
+  or WSL registration, or possibly due to the ordering of definitions,
+  then one troubleshooting step is to just unregister everything using
+  sudo sh -c 'echo -1 >/proc/sys/fs/binfmt_misc/status' and try again.
+
 SEE ALSO
 
-  https://justine.storage.googleapis.com/ape.html
+  https://justine.lol/ape.html
 
 EOF
   kill $1

build/sanitycheck2

@@ -1,16 +0,0 @@
-MZboop=123
-exit $MZboop
-                                                                                
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- 
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