Fix potential buffer overflow in strncat()

When using clang/llvm 3.8 to compile flex, the following warning is
emitted:

main.c:378:27: warning: the value of the size argument in 'strncat' is too large, might lead to a buffer overflow [-Wstrncat-size]
                                        strncat(m4_path, m4, sizeof(m4_path));
                                                             ^~~~~~~~~~~~~~~
main.c:378:27: note: change the argument to be the free space in the destination buffer minus the terminating null byte
                                        strncat(m4_path, m4, sizeof(m4_path));
                                                             ^~~~~~~~~~~~~~~
                                                             sizeof(m4_path) - strlen(m4_path) - 1

Fix it up by using the solution proposed by the warning message.

0 files changed, 0 insertions, 0 deletions