tools: make json-c optional

This shouldn't be a requirement to compile anything else. Stop requiring
it for building anything, and assume the user just wants to compile the
main project.

Signed-off-by: Richard Acayan <[email protected]>

Author: flamingradian

tools/meson.build

@@ -1,6 +1,8 @@
-json_c = dependency('json-c')
+json_c = dependency('json-c', required : false)
 
-executable('sscregistrygen',
-  'sscregistrygen.c',
-  c_args : cflags,
-  dependencies : [json_c])
+if json_c.found()
+  executable('sscregistrygen',
+    'sscregistrygen.c',
+    c_args : cflags,
+    dependencies : [json_c])
+endif