Better workaround for CFLAGS issues from #14072; fixes #14162

When I applied patch fcc78e5f8a, I somehow broke
stack trace symbols on Linux.  I'll leave it to others to figure out
why that happens.  This should be better.  Really.

Fixes bug 14162; bug not in any released version of Tor.

Makefile.am

@@ -19,6 +19,7 @@ noinst_PROGRAMS=
 DISTCLEANFILES=
 bin_SCRIPTS=
 AM_CPPFLAGS=
+AM_CFLAGS = @TOR_SYSTEMD_CFLAGS@
 include src/include.am
 include doc/include.am
 include contrib/include.am

configure.ac

@@ -130,9 +130,10 @@ fi
 
 if test x$have_systemd = xyes; then
     AC_DEFINE(HAVE_SYSTEMD,1,[Have systemd])
-    CFLAGS="${CFLAGS} ${SYSTEMD_CFLAGS}"
+    TOR_SYSTEMD_CFLAGS="${SYSTEMD_CFLAGS}"
     TOR_SYSTEMD_LIBS="${SYSTEMD_LIBS}"
 fi
+AC_SUBST(TOR_SYSTEMD_CFLAGS)
 AC_SUBST(TOR_SYSTEMD_LIBS)
 
 if test x$enable_systemd = xyes -a x$have_systemd != xyes ; then
@@ -1543,7 +1544,7 @@ fi
 if test "$GCC" = yes; then
   # Disable GCC's strict aliasing checks.  They are an hours-to-debug
   # accident waiting to happen.
-  CFLAGS="$CFLAGS -Wall -fno-strict-aliasing -g -O2"
+  CFLAGS="$CFLAGS -Wall -fno-strict-aliasing"
 else
   # Override optimization level for non-gcc compilers
   CFLAGS="$CFLAGS -O"