[sr-dev] [kamailio/kamailio] getting an error while install kamailio5.1 on ubntu 18.4 (#1602)

flex -o core/lex.yy.c core/cfg.lex CC (gcc) [kamailio] core/lex.yy.o CC (gcc) [kamailio] core/cfg.tab.o LD (gcc) [kamailio] kamailio CC (gcc) [M db_mysql.so] km_val.o CC (gcc) [M db_mysql.so] my_fld.o In file included from my_fld.c:22:0: my_fld.h:37:2: error: unknown type name ‘my_bool’ my_bool is_null; ^~~~~~~ ../../Makefile.rules:100: recipe for target 'my_fld.o' failed make[2]: *** [my_fld.o] Error 1 Makefile:511: recipe for target 'modules' failed make[1]: *** [modules] Error 1 make[1]: Leaving directory '/usr/local/src/kamailio-5.1/kamailio/src' Makefile:27: recipe for target 'all' failed make: *** [all] Error 2