Fix 64-bit shifts where long only has 32-bit size

Fix 64-bit shifts where long only has 32-bit size

On systems where long has 32-bit size you get these failures:

print 1 << (unsigned long long) 0xffffffffffffffff
Cannot export value 18446744073709551615 as 32-bits unsigned integer (must be between 0 and 4294967295)
(gdb) FAIL: gdb.base/bitshift.exp: lang=c: max-uint64: print 1 << (unsigned long long) 0xffffffffffffffff
print 1 >> (unsigned long long) 0xffffffffffffffff
Cannot export value 18446744073709551615 as 32-bits unsigned integer (must be between 0 and 4294967295)
(gdb) FAIL: gdb.base/bitshift.exp: lang=c: max-uint64: print 1 >> (unsigned long long) 0xffffffffffffffff
print -1 << (unsigned long long) 0xffffffffffffffff
Cannot export value 18446744073709551615 as 32-bits unsigned integer (must be between 0 and 4294967295)
(gdb) FAIL: gdb.base/bitshift.exp: lang=c: max-uint64: print -1 << (unsigned long long) 0xffffffffffffffff
print -1 >> (unsigned long long) 0xffffffffffffffff
Cannot export value 18446744073709551615 as 32-bits unsigned integer (must be between 0 and 4294967295)
(gdb) FAIL: gdb.base/bitshift.exp: lang=c: max-uint64: print -1 >> (unsigned long long) 0xffffffffffffffff

Fixed by changing the number-of-bits variable to ULONGEST.

Approved-By: Tom Tromey <tom@tromey.com>