Fx misc compiler warnings

Fx misc compiler warnings

src/vnstat.h:7:33: warning: identifier ‘delete’ conflicts with C++ keyword [-Wc++-compat]

src/ifinfo.c:61:13: warning: request for implicit conversion from ‘void *’ to ‘char *’ not permitted in C++ [-Wc++-compat]

src/dbxml.c:110:16: warning: initialization discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]

src/dbjson.c:134:16: warning: initialization discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]

src/common.c:270:6: warning: function might be candidate for attribute ‘noreturn’ [-Wsuggest-attribute=noreturn]

src/misc.c:309:32: warning: initialization discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]

src/ibw.c:34:5: warning: request for implicit conversion from ‘void *’ to ‘ibwnode * {aka struct ibwnode *}’ not permitted in C++ [-Wc++-compat]

src/image.c:68:17: warning: passing argument 1 of ‘colorinitcheck’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]

src/dbcache.c:26:4: warning: request for implicit conversion from ‘void *’ to ‘datanode * {aka struct datanode *}’ not permitted in C++ [-Wc++-compat]

src/ifinfo.c:358:4: warning: unsuffixed float constant [-Wunsuffixed-float-constants]

src/common.c:173:14: warning: nested extern declaration of ‘timezone’ [-Wnested-externs]
src/common.c:173:14: warning: redundant redeclaration of ‘timezone’ [-Wredundant-decls]