Allow init of app protocols w/o any hostnames set. #2855

Job	Run time
Python Bindings (ubuntu-latest)	1m 21s
Test Utils (ubuntu-latest)	2m 18s
ubuntu-latest x86_64 --with-local-libgcrypt cc	8m 10s
ubuntu-latest x86_64 cc	7m 58s
ubuntu-20.04 x86_64 --with-local-libgcrypt cc	7m 17s
ubuntu-20.04 x86_64 cc	9m 30s
macOS-latest x86_64 --with-local-libgcrypt cc	7m 6s
macOS-latest x86_64 cc	6m 4s
macos-11 x86_64 --with-local-libgcrypt cc	7m 12s
macos-11 x86_64 cc	6m 25s
windows-latest x86_64 --with-local-libgcrypt cc	22m 15s
windows-latest x86_64 cc	12m 41s
ubuntu-20.04 x86_64 gcc-7 --with-pcre --with-maxminddb --with-sanitizer	17m 33s
ubuntu-22.04 x86_64 gcc-12 --with-pcre --with-maxminddb --with-sanitizer --with-lto-and-gold-linker	24m 21s
ubuntu-20.04 x86_64 clang-7 --with-pcre --with-maxminddb --with-sanitizer	26m 29s
ubuntu-22.04 x86_64 clang-14 --with-pcre --with-maxminddb --with-sanitizer --with-lto-and-gold-linker	22m 59s
ubuntu-latest x86_64 cc --with-pcre --with-maxminddb --with-thread-sanitizer	51m 48s
ubuntu-latest x86_64 cc --with-pcre --with-maxminddb --with-sanitizer nBPF	17m 1s
ubuntu-22.04 x86_64 clang-14 --with-pcre --with-maxminddb --with-memory-sanitizer	55m 54s
macOS-latest x86_64 cc --with-pcre --with-maxminddb	6m 37s
macos-12 x86_64 cc --with-pcre --with-maxminddb	9m 5s
ubuntu-latest arm64 cc --with-pcre --with-maxminddb	37m 32s
ubuntu-latest armhf cc --with-pcre --with-maxminddb --with-sanitizer	1h 42m 27s
ubuntu-latest s390x cc --with-pcre --with-maxminddb	31m 58s
	8h 22m 1s

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