Change DevBuildType to also enable Wsuggest-override on clang if version >= 11

I came across this and figured, since clang >=11 supports -Wsuggest-override I might as well send in a quick patch.

added build system label

changed milestone to %v35r3

approved this merge request

added lhcb-gaudi-head label

• [2021-03-25 00:06] Validation started with lhcb-gaudi-head#2888
• [2021-03-25 01:08] Validation started with lhcb-run2-gaudi-head#96
• [2021-03-26 00:04] Validation started with lhcb-gaudi-head#2889
• [2021-03-26 00:45] Validation started with lhcb-run2-gaudi-head#97
• [2021-03-26 01:07] Validation started with lhcb-gaudi-head#2889
• [2021-03-27 00:06] Validation started with lhcb-gaudi-head#2890
• [2021-03-27 00:58] Validation started with lhcb-run2-gaudi-head#98
• [2021-03-28 00:03] Validation started with lhcb-gaudi-head#2891
• [2021-03-28 00:09] Validation started with lhcb-run2-gaudi-head#99
• [2021-03-29 00:06] Validation started with lhcb-gaudi-head#2892
• [2021-03-30 00:04] Validation started with lhcb-gaudi-head#2893
• [2021-03-31 00:05] Validation started with lhcb-gaudi-head#2894
• [2021-03-31 01:02] Validation started with lhcb-run2-gaudi-head#100
• [2021-04-01 00:30] Validation started with lhcb-gaudi-head#2895
• [2021-04-01 01:14] Validation started with lhcb-run2-gaudi-head#101
• [2021-04-02 00:07] Validation started with lhcb-gaudi-head#2896
• [2021-04-02 00:47] Validation started with lhcb-run2-gaudi-head#102
• [2021-04-02 01:22] Validation started with lhcb-run2-gaudi-head#102
• [2021-04-03 00:13] Validation started with lhcb-run2-gaudi-head#103
• [2021-04-03 00:43] Validation started with lhcb-run2-gaudi-head#103

assigned to @clemenci

merged

mentioned in commit fc36979c