add C compiler and C include checks for calc

Fixed have_statfs optional executable file extension ${EXT{ in
the ${UTIL_PROGS} make variable.

Prevented the "fake boolean value" when <stdbool.h> is missing,
from complicating C compilers post c17 standard.

Test if <stdint.h> exists and set HAVE_STDINT_H accordingly
in have_stdint.h.  Added HAVE_STDINT_H to allow one to force
this value.

Test if <inttypes.h> exists and set HAVE_INTTYPES_H accordingly
in have_inttypes.h.  Added HAVE_INTTYPES_H to allow one to force
this value.

Added c_chk.c to check the compiler and C include for calc
requirements.  If you are unable to compile this program, or
if this program when compiles does not exit 0, then your C
compiler and/or C include fails to meet calc requirements.
Compilers that are at least c99 MUST be able to compile this
program such that when run will exit 0.

The "make hsrc" file will attempt to compile and run c_chk and
will warn if the C compiler and/or C include fails to meet
calc requirements.  The "make debug" system will run c_chk -c
to print information about the C compiler and C include.
Currently failure to compile cc_chk.c or c_chk exiting non-0
will just print "WARNING!!" strings to stderr.

bool.h

@@ -42,7 +42,9 @@
 #if !defined(HAVE_STDBOOL_H)
 
 /* fake a <stdbool.h> header file */
-typedef unsigned char bool;	/* fake boolean value */
+#if __STDC_VERSION__ <= 201710
+typedef unsigned int bool;	/* fake boolean typedef */
+#endif /* __STDC_VERSION__ <= 201710 */
 #undef true
 #define true ((bool)(1))
 #undef false