/// $CompilerFlags: find_compiler_flags("libmaxminddb" "")
/// $LinkerFlags: find_linker_flags("libmaxminddb" "-lmaxminddb")
+/// $PackageInfo: require_system("arch") libmaxminddb pkgconf
/// $PackageInfo: require_system("darwin") libmaxminddb pkg-config
/// $PackageInfo: require_system("debian" "9.0") libmaxminddb-dev pkg-config
/// $PackageInfo: require_system("ubuntu" "16.04") libmaxminddb-dev pkg-config
/// $LinkerFlags: -llber -lldap_r
+/// $PackageInfo: require_system("arch") libldap
/// $PackageInfo: require_system("centos") openldap-devel
/// $PackageInfo: require_system("debian") libldap2-dev
/// $PackageInfo: require_system("ubuntu") libldap2-dev
/// $CompilerFlags: execute("mysql_config --include" "MYSQL_CXXFLAGS")
/// $LinkerFlags: execute("mysql_config --libs_r" "MYSQL_LDFLAGS" "-lmysqlclient")
+/// $PackageInfo: require_system("arch") mariadb-libs
/// $PackageInfo: require_system("centos" "6.0" "6.99") mysql-devel
/// $PackageInfo: require_system("centos" "7.0") mariadb-devel
/// $PackageInfo: require_system("darwin") mysql-connector-c
/// $CompilerFlags: -Iexecute("pg_config --includedir" "POSTGRESQL_INCLUDE_DIR")
/// $LinkerFlags: -Lexecute("pg_config --libdir" "POSTGRESQL_LIBRARY_DIR") -lpq
+/// $PackageInfo: require_system("arch") postgresql-libs
/// $PackageInfo: require_system("centos") postgresql-devel
/// $PackageInfo: require_system("darwin") postgresql
/// $PackageInfo: require_system("debian") libpq-dev
/// $CompilerFlags: execute("pcre-config --cflags" "PCRE_CXXFLAGS")
/// $LinkerFlags: execute("pcre-config --libs" "PCRE_LDFLAGS" "-lpcre")
+/// $PackageInfo: require_system("arch") pcre
/// $PackageInfo: require_system("centos") pcre-devel
/// $PackageInfo: require_system("darwin") pcre
/// $PackageInfo: require_system("debian") libpcre3-dev
/// $CompilerFlags: find_compiler_flags("re2" "")
/// $LinkerFlags: find_linker_flags("re2" "-lre2")
+/// $PackageInfo: require_system("arch") pkgconf re2
/// $PackageInfo: require_system("darwin") pkg-config re2
/// $PackageInfo: require_system("debian" "8.0") libre2-dev pkg-config
/// $PackageInfo: require_system("ubuntu" "15.10") libre2-dev pkg-config
/// $CompilerFlags: find_compiler_flags("tre")
/// $LinkerFlags: find_linker_flags("tre" "-ltre")
+/// $PackageInfo: require_system("arch") pkgconf tre
/// $PackageInfo: require_system("darwin") pkg-config tre
/// $PackageInfo: require_system("debian") libtre-dev pkg-config
/// $PackageInfo: require_system("ubuntu") libtre-dev pkg-config
/// $CompilerFlags: find_compiler_flags("sqlite3")
/// $LinkerFlags: find_linker_flags("sqlite3" "-lsqlite3")
+/// $PackageInfo: require_system("arch") pkgconf sqlite
/// $PackageInfo: require_system("centos") pkgconfig sqlite-devel
/// $PackageInfo: require_system("darwin") pkg-config sqlite3
/// $PackageInfo: require_system("debian") libsqlite3-dev pkg-config
/// $LinkerFlags: find_linker_flags("gnutls" "-lgnutls")
/// $LinkerFlags: require_version("gnutls" "1.0" "2.12") execute("libgcrypt-config --libs" "LIBGCRYPT_LDFLAGS")
+/// $PackageInfo: require_system("arch") gnutls pkgconf
/// $PackageInfo: require_system("centos") gnutls-devel pkgconfig
/// $PackageInfo: require_system("darwin") gnutls pkg-config
/// $PackageInfo: require_system("debian" "1.0" "7.99") libgcrypt11-dev
/// $LinkerFlags: -lmbedtls
+/// $PackageInfo: require_system("arch") mbedtls
/// $PackageInfo: require_system("darwin") mbedtls
/// $PackageInfo: require_system("debian" "9.0") libmbedtls-dev
/// $PackageInfo: require_system("ubuntu" "16.04") libmbedtls-dev
/// $CompilerFlags: find_compiler_flags("openssl")
/// $LinkerFlags: find_linker_flags("openssl" "-lssl -lcrypto")
+/// $PackageInfo: require_system("arch") openssl pkgconf
/// $PackageInfo: require_system("centos") openssl-devel pkgconfig
/// $PackageInfo: require_system("darwin") openssl pkg-config
/// $PackageInfo: require_system("debian") libssl-dev openssl pkg-config