Somehow the standard C header files seem to have gone missing.
/usr/include/ used to include inttypes.h, sys/types.h, stdlib.h, string.h and a myriad of other standard C files.
locate still shows these files present in /usr/include until I ran updatedb.
How do I recover these files? I tried re-installing gcc using apt-get.
find /usr/include -name "*.h" | wc -l? - Elliott Frisch