Fix "unknown option" warnings on GCC and older Clang

[fredmorcos]

Short description

[283/464] Compiling C++ object pdns/libdnstcpbench.a.p/dnstcpbench.cc.o
../pdns/dnstcpbench.cc:27:32: warning: unknown option after ‘#pragma GCC diagnostic’ kind [-Wpragmas]
   27 | #pragma GCC diagnostic ignored "-Wdeprecated-copy-with-user-provided-copy"
      |                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[291/464] Compiling C++ object pdns/libdnsscope.a.p/dnsscope.cc.o
In file included from ../pdns/dnsscope.cc:27:
../pdns/histog.hh:4:32: warning: unknown option after ‘#pragma GCC diagnostic’ kind [-Wpragmas]
    4 | #pragma GCC diagnostic ignored "-Wdeprecated-copy-with-user-provided-copy"
      |                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[305/464] Compiling C++ object pdns/libdnsbulktest.a.p/dnsbulktest.cc.o
../pdns/dnsbulktest.cc:27:32: warning: unknown option after ‘#pragma GCC diagnostic’ kind [-Wpragmas]
   27 | #pragma GCC diagnostic ignored "-Wdeprecated-copy-with-user-provided-copy"
      |                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Checklist

I have:

• read the CONTRIBUTING.md document
• compiled this code
• tested this code
• included documentation (including possible behaviour changes)
• documented the code
• added or modified regression test(s)
• added or modified unit test(s)

[coveralls]

Pull Request Test Coverage Report for Build 7196200024

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 20 unchanged lines in 5 files lost coverage.
• Overall coverage increased (+0.01%) to 57.689%

---

Files with Coverage Reduction	New Missed Lines	%
modules/gpgsqlbackend/gpgsqlbackend.cc	1	88.62%
pdns/tcpiohandler.cc	2	66.5%
pdns/packethandler.cc	3	73.24%
pdns/iputils.cc	4	45.31%
ext/luawrapper/include/LuaContext.hpp	10	13.72%

Totals
Change from base Build 7184070321:	0.01%
Covered Lines:	107590
Relevant Lines:	155147

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💛 - Coveralls