Check fib() overflow in bellard.otccex.c

Whereas fact() (factorial) is an overflow if n > 12 the Fibonacci is an
overflow if n > 48. In this case it reports an empty string - when it
finally finishes. For instance if you use n = 99 it takes a long time to
finish.  Since n == 49 prints an empty value we check for overflow just
like the author did for factorial.

Add compilation of bellard.otccex.c to Makefile; this can be compiled as
64-bit so we no longer specify -m32 in ARCH but instead we do that
explicitly for bellard.c. This way users can at least enjoy the
supplementary program even if not by the bellard.c directly compiling
and executing it.

2001/bellard/Makefile

@@ -55,7 +55,7 @@ CSTD= -std=gnu99
 # Some entries require 32-bitness: ARCH= -m32
 # Some entries require 64-bitness: ARCH= -m64
 #
-ARCH= -m32
+ARCH= 
 
 # Defines that are needed to compile
 #
@@ -131,6 +131,11 @@ all: data ${TARGET}
 	supernova deep_magic magic charon pluto
 
 ${PROG}: ${PROG}.c
+	@echo "WARNING: ${PROG}.c must be compiled as 32-bit to use with the entry itself;"
+	@echo "if you cannot use -m32 this will NOT work!"
+	${CC} ${CFLAGS} -m32 $< -o $@ ${LIBS}
+
+${PROG}.otccex: ${PROG}.otccex.c
 	${CC} ${CFLAGS} $< -o $@ ${LIBS}
 
 # alternative executable