Change where LHCB_UNUSED_SUBDIR_MESSAGE_TYPE is initialized

so that it is possible to override locally the value with a regular variable (and same for LHCB_UNUSED_SOURCE_MESSAGE_TYPE)

Closes #190 (closed)

added Build enhancement labels

mentioned in merge request !3424 (merged)

added all-slots label

mentioned in merge request !3357 (merged)

• [2022-05-12 00:58] Validation started with lhcb-run2-gaudi-head#325
• [2022-05-12 00:59] Validation started with lhcb-run2-patches-dev4#1054
• [2022-05-12 01:03] Validation started with lhcb-run2-patches#1142
• [2022-05-13 00:39] Validation started with lhcb-run2-patches-dev4#1055
• [2022-05-14 09:18] Validation started with lhcb-run2-patches-dev4#1056
• [2022-05-15 00:17] Validation started with lhcb-run2-patches-dev4#1057
• [2022-05-16 00:31] Validation started with lhcb-run2-patches-dev4#1058
• [2022-05-17 00:24] Validation started with lhcb-run2-patches-dev4#1059
• [2022-05-18 00:29] Validation started with lhcb-run2-patches-dev4#1060
• [2022-05-19 00:37] Validation started with lhcb-run2-gaudi-head#326
• [2022-05-19 00:37] Validation started with lhcb-run2-patches#1143
• [2022-05-19 00:37] Validation started with lhcb-run2-patches-dev4#1061
• [2022-05-20 00:34] Validation started with lhcb-run2-patches-dev4#1062

mentioned in commit bdfffdb3

merged