Add shm_size to build-options (issue #3866)

 * Add shm_size to build configuration
 * Make it possible to enlarge/customize shm size during build
 * Value in bytes, or use string like "512M" or "1G" ...
 * Add to compose format 2.3 and (provisionally) >=3.5 format
 * Add automated test for shm_size in build-opts

Signed-off-by: Marc van den Hoogen <marc@vandenhoogen.eu>

Made unit tests compatible with previously added shm_size build-option

Signed-off-by: Marc van den Hoogen <marc@vandenhoogen.eu>

Also support shm_size build-opt when conf override

Signed-off-by: Marc van den Hoogen <marc@vandenhoogen.eu>

Automated test for shm_size build-option

Signed-off-by: Marc van den Hoogen <marc@vandenhoogen.eu>

Schema 3.4, add shm_size to schema 2.3, updated const.py

Signed-off-by: Marc van den Hoogen <marc@vandenhoogen.eu>

Corrected typo in config_schema_v3.4

Signed-off-by: Marc van den Hoogen <marc@vandenhoogen.eu>

Add support for g/m/k units for shm_size in build-opts

Signed-off-by: Marc van den Hoogen <marc@vandenhoogen.eu>

Reorder imports in service.py

Signed-off-by: Marc van den Hoogen <marc@vandenhoogen.eu>

compose/config/config.py

@@ -1020,6 +1020,7 @@ def to_dict(service):
     md.merge_scalar('dockerfile')
     md.merge_scalar('network')
     md.merge_scalar('target')
+    md.merge_scalar('shm_size')
     md.merge_mapping('args', parse_build_arguments)
     md.merge_field('cache_from', merge_unique_items_lists, default=[])
     md.merge_mapping('labels', parse_labels)

compose/config/config_schema_v2.3.json

@@ -91,7 +91,8 @@
                 "labels": {"$ref": "#/definitions/list_or_dict"},
                 "cache_from": {"$ref": "#/definitions/list_of_strings"},
                 "network": {"type": "string"},
-                "target": {"type": "string"}
+                "target": {"type": "string"},
+                "shm_size": {"type": ["integer", "string"]}
               },
               "additionalProperties": false
             }