Check for <bluetooth/bluetooth.h> presence during configure.

[burghardt]

To avoid build error on absence of included <bluetooth/bluetooth.h> file during make stage check for this file in configure stage.

This will avoid following build error.

g++ -DHAVE_CONFIG_H -I. -I.. -fPIC -Wall -Wextra -std=c++11 -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -pthread -I/usr/include/libmount -I/usr/include/blkid -I/usr/include/uuid -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -g -O2 -MT libggk_a-HciSocket.o -MD -MP -MF .deps/libggk_a-HciSocket.Tpo -c -o libggk_a-HciSocket.o test -f 'HciSocket.cpp' || echo './'HciSocket.cpp HciSocket.cpp:33:10: fatal error: bluetooth/bluetooth.h: No such file or directory #include <bluetooth/bluetooth.h> ^~~~~~~~~~~~~~~~~~~~~~~ compilation terminated. make[2]: *** [Makefile:601: libggk_a-HciSocket.o] Error 1 make[2]: Leaving directory '/home/user/packages/gobbledegook/src' make[1]: *** [Makefile:368: all-recursive] Error 1 make[1]: Leaving directory '/home/user/packages/gobbledegook' make: *** [Makefile:309: all] Error 2