We are inconsistent on whether a cast operator should be separated
from its argument by a space.  As a unary prefix operator, casts bind
with relatively tight precedence, where only postfix operations
(including function calls) come higher.  We generally don't use a
space after other prefix operators (*, &, ~, and unary - tend to not
be followed by space; we are less consistent on !, but that would be a
separate patch).

Furthermore, we've already decided (in commit b5101fbc

) that we prefer
spaces before function invocations.  At the time, discussion on the
list[1] pointed out that thanks to the complexity of C with its
context-sensitive parsing needing to know whether an identifier is a
type name, you would be able to tell the difference between a
2-argument function call with two parameters through a function
pointer (or intentional function-like macro suppression):

  (foo) (bar, baz)

from the (admittedly rare) application of a cast operator to the
results of a comma operator:

  (foo)(bar, baz)

if we consistently avoid spaces after casts.

Determining cast operators is not always trivial, but the regex used
below seems to have a pretty low false positive rate (lines it selects
usually are casts and not in a comment line), and can be modified by
removing the space to see where we already had casts without a
space. (Obviously, I can't tell how many false negatives there are of
casts I missed out on).  While this changes more lines than would be
done by instead always using a space in a cast, it is still manageable
to do a bulk change.

$ git grep '\(_t\|int\|long\|signed\|char\|\*\)) [a-zA-Z0-9&"]' -- \
  '**/*.[hc]' '**/*.ml' | grep -v '^ */\?\*'

'git show -w' shows that this change is whitespace only.

[1] https://listman.redhat.com/archives/libguestfs/2023-February/030771.html

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20230524021244.261832-1-eblake@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Acked-by: Richard W.M. Jones <rjones@redhat.com>