[PATCH-for-9.0] meson: Allow building binary with no target-specific files in hw/

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

Allow  building a qemu-system-foo binary with target-agnostic
only HW models.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
Although this is for 9.0, I wanted to post it today to celebrate :)

Once reviewed I plan to queue it via my heterogenenous-cpus tree.
---
 meson.build | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/meson.build b/meson.build
index ec01f8b138..9ccfb091e7 100644
--- a/meson.build
+++ b/meson.build
@@ -3772,9 +3772,11 @@ foreach target : target_dirs
     arch_deps += t.dependencies()
 
     hw_dir = target_name == 'sparc64' ? 'sparc64' : target_base_arch
-    hw = hw_arch[hw_dir].apply(config_target, strict: false)
-    arch_srcs += hw.sources()
-    arch_deps += hw.dependencies()
+    if hw_arch.has_key(hw_dir)
+      hw = hw_arch[hw_dir].apply(config_target, strict: false)
+      arch_srcs += hw.sources()
+      arch_deps += hw.dependencies()
+    endif
 
     arch_srcs += config_devices_h[target]
     link_args += ['@block.syms', '@qemu.syms']
-- 
2.41.0