Loadable: Add const qualifier to member function #2066

Job	Run time
compiler-20 (gcc-8, g++-8, g++-8)	3m 47s
compiler-20 (gcc-10, g++-10, g++-10)	3m 50s
ASan-22	5m 0s
library-20 (-Dtls=gnutls -Dsessionlib=xsmp -Dmigemo=enabled -Dalsa=enabled -Dpangolayout=enabled,...	4m 27s
compiler-20 (clang-7, clang++-7, clang-7)	4m 2s
compiler-22 (gcc-12, g++-12, g++-12)	4m 45s
library-20 (-Dtls=openssl -Dsessionlib=no -Dmigemo=enabled -Dcompat_cache_dir=disabled, libssl-de...	4m 28s
compiler-20 (clang-8, clang++-8, clang-8)	3m 51s
compiler-22 (clang-11, clang++-11, clang-11)	4m 30s
library-20 (-Dtls=openssl -Dsessionlib=xsmp -Dalsa=enabled -Dpangolayout=enabled, libssl-dev liba...	4m 20s
library-22 (-Dtls=gnutls -Dsessionlib=xsmp -Dmigemo=enabled -Dalsa=enabled -Dpangolayout=enabled,...	4m 0s
compiler-20 (clang-9, clang++-9, clang-9)	4m 8s
compiler-22 (clang-12, clang++-12, clang-12)	4m 39s
library-22 (-Dtls=openssl -Dsessionlib=no -Dmigemo=enabled -Dcompat_cache_dir=disabled, libssl-de...	3m 54s
compiler-20 (clang-10, clang++-10, clang-10)	4m 25s
compiler-22 (clang-13, clang++-13, clang-13)	5m 2s
library-22 (-Dtls=openssl -Dsessionlib=xsmp -Dalsa=enabled -Dpangolayout=enabled, libssl-dev liba...	3m 51s
manual-build	17s
compiler-22 (clang-14, clang++-14, clang-14)	4m 39s
compiler-22 (clang-15, clang++-15, clang-15)	4m 57s
	1h 22m 52s

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