alert: Fix compilation error with musl
alert: Fix compilation error with musl

  CC       profiles/alert/bluetoothd-server.o
In file included from profiles/alert/server.c:49:0:
./src/textfile.h:24:1: error: unknown type name 'mode_t'
 int create_file(const char *filename, const mode_t mode);
 ^
Makefile:7469: recipe for target 'profiles/alert/bluetoothd-server.o'
    failed
make[1]: *** [profiles/alert/bluetoothd-server.o] Error 1
Makefile:3072: recipe for target 'all' failed

ComputeCycles/bluez,ComputeCycles/bluez,pstglia/external-bluetooth-bluez,pstglia/external-bluetooth-bluez,ComputeCycles/bluez,pstglia/external-bluetooth-bluez,pkarasev3/bluez,pstglia/external-bluetooth-bluez,mapfau/bluez,pkarasev3/bluez,silent-snowman/bluez,silent-snowman/bluez,silent-snowman/bluez,pkarasev3/bluez,mapfau/bluez,ComputeCycles/bluez,pkarasev3/bluez,mapfau/bluez,silent-snowman/bluez,mapfau/bluez