When -Werror=format-truncation is enabled, various warnings break the
build like:

[Compiling library-trans-ip/C_TransIP.cpp]
library-trans-ip/C_TransIP.cpp: In member function 'void C_TransIP::analyze_optional_init_string(char*)':
library-trans-ip/C_TransIP.cpp:676:6: error: '%s' directive output may be truncated writing up to 254 bytes into a region of size 56 [-Werror=format-truncation=]
 void C_TransIP::analyze_optional_init_string(char *P_buf) {
      ^~~~~~~~~
library-trans-ip/C_TransIP.cpp:66:10: note: 'snprintf' output between 46 and 300 bytes into a destination of size 100
  snprintf(L_msg, 100, (char*)(m), (P1)) ; \
  ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
library-trans-ip/C_TransIP.cpp:710:9: note: in expansion of macro 'LOG_ALL_P1'
         LOG_ALL_P1("Unknown parameter value for close-wait-ms: [%s]", L_tmp);
         ^~~~~~~~~~
library-trans-ip/C_TransIP.cpp: In member function 'int C_TransIP::extract_ip_addr(T_pIpAddr)':
library-trans-ip/C_TransIP.cpp:846:5: error: '%s' directive output may be truncated writing up to 1023 bytes into a region of size 84 [-Werror=format-truncation=]
 int C_TransIP::extract_ip_addr(T_pIpAddr P_pIpAddr) {
     ^~~~~~~~~
library-trans-ip/C_TransIP.cpp:66:10: note: 'snprintf' output between 18 and 1041 bytes into a destination of size 100
...
cc1plus: all warnings being treated as errors
make[1]: *** [.../seagull/trunk/src/work-1.8.3/dep-libtrans_ip.so.mk:55: .../seagull/trunk/src/work-1.8.3/C_TransIP.o] Error 1

The longest string being snprintf'ed is up to just over 1000 bytes,
so this simply defines the error/log message size to 1200 bytes.