Drop the deprecated lm32 target

Target lm32 was deprecated in commit d8498005122, v5.2.0.  See there
for rationale.

Some of its code lives on in device models derived from milkymist
ones: hw/char/digic-uart.c and hw/display/bcm2835_fb.c.

Cc: Michael Walle <michael@walle.cc>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20210503084034.3804963-2-armbru@redhat.com>
Acked-by: Michael Walle <michael@walle.cc>
[Trivial conflicts resolved, reST markup fixed]
diff --git a/meson.build b/meson.build
index eeb82a4..8e16e05 100644
--- a/meson.build
+++ b/meson.build
@@ -847,7 +847,7 @@
                            link_args: config_host['VTE_LIBS'].split())
 endif
 x11 = not_found
-if gtkx11.found() or 'lm32-softmmu' in target_dirs
+if gtkx11.found()
   x11 = dependency('x11', method: 'pkg-config', required: gtkx11.found(),
                    kwargs: static_kwargs)
 endif
@@ -1210,7 +1210,6 @@
   'i386' : ['CONFIG_I386_DIS'],
   'x86_64' : ['CONFIG_I386_DIS'],
   'x32' : ['CONFIG_I386_DIS'],
-  'lm32' : ['CONFIG_LM32_DIS'],
   'm68k' : ['CONFIG_M68K_DIS'],
   'microblaze' : ['CONFIG_MICROBLAZE_DIS'],
   'mips' : ['CONFIG_MIPS_DIS'],