meson: pass more options directly as -D

If an option is not used anywhere by the configure script, it can be just
added to $meson_options even if it is not parsed by the automatically
generated bits in scripts/meson-buildoptions.sh.

The only slightly tricky case is $debug, where the

  if test "$fortify_source" = "yes" ; then
    QEMU_CFLAGS="-U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 $QEMU_CFLAGS"
    debug=no
  fi

assignment is dead; configure sets fortify_source=no whenever debug=yes.

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

scripts/meson-buildoptions.py

@@ -33,6 +33,8 @@ SKIP_OPTIONS = {
 }
 
 OPTION_NAMES = {
+    "b_coverage": "gcov",
+    "b_lto": "lto",
     "malloc": "enable-malloc",
     "pkgversion": "with-pkgversion",
     "qemu_firmwarepath": "firmwarepath",
@@ -41,6 +43,8 @@ OPTION_NAMES = {
 }
 
 BUILTIN_OPTIONS = {
+    "b_coverage",
+    "b_lto",
     "datadir",
     "includedir",
     "libdir",