Fix fakeroot build by using od(1) to check 64-bit ELFs (#943)

bin/package:
- Use od(1) to check the ELF header if the file command fails.
  This allows ksh to build and install correctly in fakeroot
  environments without encountering bogus seccomp restrictions.
  - Check the first five bytes to guarantee it's actually an ELF
    binary.
  - Return 'Unknown bits' if it's neither a 64-bit ELF nor 32-bit
    ELF (i.e. it could be anything). This isn't functionally
    different but is better for clarity.

Resolves: #919

Author: JohnoKing

bin/package

@@ -1527,7 +1527,18 @@ int b(void) { return 0; }
 					echo 'int main(void) { return 0; }' > $tmp.a.c
 					checkcc
 					$cc $CCFLAGS -o $tmp.a.exe $tmp.a.c </dev/null >/dev/null 2>&1
-					file $tmp.a.exe 2>/dev/null | sed "s/$tmp\.a\.exe//g"  )
+					file_result=$(file $tmp.a.exe 2>/dev/null | sed "s/$tmp\.a\.exe//g") || true
+					# Use od(1) to check the ELF header directly if file(1) failed
+					if test -z "$file_result" && test "$(uname -s | sed 's/-.*//')" != CYGWIN
+					then	elfbytes=$(od -An -tx1 -N 5 $tmp.a.exe | tr -d ' 	\n')
+						if test "$elfbytes" = "7f454c4602"
+						then echo "ELF 64-bit"
+						elif test "$elfbytes" = "7f454c4601"
+						then echo "ELF 32-bit"
+						else echo "Unknown bits"
+						fi
+					else	echo "$file_result"
+					fi )
 				case $bits in
 				*\ 64-bit* | *\ 64\ bit* | *\ 64bit*)
 					bits=64 ;;