Iconv: Fix incorrect reset for errno value #2090

Job	Run time
ASan-22	4m 50s
compiler-22 (gcc-12, g++-12, g++-12)	5m 2s
library-20 (-Dtls=gnutls -Dsessionlib=xsmp -Dmigemo=enabled -Dalsa=enabled -Dpangolayout=enabled,...	4m 22s
compiler-22 (clang-11, clang++-11, clang-11)	4m 41s
compiler-20 (gcc-8, g++-8, g++-8)	3m 47s
library-20 (-Dtls=openssl -Dsessionlib=no -Dmigemo=enabled -Dcompat_cache_dir=disabled, libssl-de...	4m 43s
library-22 (-Dtls=gnutls -Dsessionlib=xsmp -Dmigemo=enabled -Dalsa=enabled -Dpangolayout=enabled,...	3m 53s
compiler-20 (gcc-10, g++-10, g++-10)	3m 59s
compiler-22 (clang-12, clang++-12, clang-12)	4m 53s
library-20 (-Dtls=openssl -Dsessionlib=xsmp -Dalsa=enabled -Dpangolayout=enabled, libssl-dev liba...	4m 21s
compiler-22 (clang-13, clang++-13, clang-13)	5m 2s
compiler-20 (clang-7, clang++-7, clang-7)	3m 56s
compiler-22 (clang-14, clang++-14, clang-14)	4m 50s
library-22 (-Dtls=openssl -Dsessionlib=no -Dmigemo=enabled -Dcompat_cache_dir=disabled, libssl-de...	4m 9s
compiler-20 (clang-8, clang++-8, clang-8)	4m 3s
compiler-22 (clang-15, clang++-15, clang-15)	5m 9s
manual-build	15s
library-22 (-Dtls=openssl -Dsessionlib=xsmp -Dalsa=enabled -Dpangolayout=enabled, libssl-dev liba...	4m 12s
compiler-20 (clang-9, clang++-9, clang-9)	4m 10s
compiler-20 (clang-10, clang++-10, clang-10)	4m 30s
	1h 24m 47s

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