maint: port to gcc -std=c99 -Wstrict-prototypes

This doesn’t fix any bugs, since the code is correct as-is on all
C versions.  However, it pacifies gcc -std=c99 -Wstrict-prototypes,
which complains about a function definition without arguments
unless there’s a previous prototype with ‘(void)’.
Most (but not all) of this patch merely reverts some recent
changes to be more consistent when porting to C23.
* dfltcc.c (is_dfltcc_enabled):
* gzip.c (get_input_size_and_time):
* inflate.c (inflate_stored, inflate_fixed, inflate_dynamic):
* unpack.c (read_byte):

4 files changed, 6 insertions, 6 deletions

diff --git a/dfltcc.c b/dfltcc.c
index 0c14ad5..b9eaf5e 100644
--- a/dfltcc.c
+++ b/dfltcc.c
@@ -147,7 +147,7 @@ is_bit_set (const char *bits, int n)
 }
 
 static int
-is_dfltcc_enabled ()
+is_dfltcc_enabled (void)
 {
   char facilities[(DFLTCC_FACILITY / 64 + 1) * 8];
 
diff --git a/gzip.c b/gzip.c
index 5cfdb24..9602271 100644
--- a/gzip.c
+++ b/gzip.c
@@ -710,7 +710,7 @@ input_eof ()
 }
 
 static void
-get_input_size_and_time ()
+get_input_size_and_time (void)
 {
   ifile_size = -1;
   time_stamp.tv_nsec = -1;
diff --git a/inflate.c b/inflate.c
index f90cab5..e92bc6c 100644
--- a/inflate.c
+++ b/inflate.c
@@ -627,7 +627,7 @@ inflate_codes(struct huft *tl, struct huft *td, int bl, int bd)
 
 /* "decompress" an inflated type 0 (stored) block. */
 static int
-inflate_stored ()
+inflate_stored(void)
 {
   unsigned n;           /* number of bytes in block */
   unsigned w;           /* current window position */
@@ -683,7 +683,7 @@ inflate_stored ()
    either replace this with a custom decoder, or at least precompute the
    Huffman tables. */
 static int
-inflate_fixed ()
+inflate_fixed(void)
 {
   int i;                /* temporary variable */
   struct huft *tl;      /* literal/length code table */
@@ -733,7 +733,7 @@ inflate_fixed ()
 
 /* decompress an inflated type 2 (dynamic Huffman codes) block. */
 static int
-inflate_dynamic ()
+inflate_dynamic(void)
 {
   int i;                /* temporary variables */
   unsigned j;
diff --git a/unpack.c b/unpack.c
index 39ca75d..ba7d106 100644
--- a/unpack.c
+++ b/unpack.c
@@ -78,7 +78,7 @@ static int valid;                  /* number of valid bits in bitbuf */
 
 /* Read an input byte, reporting an error at EOF.  */
 static unsigned char
-read_byte ()
+read_byte (void)
 {
   int b = get_byte ();
   if (b < 0)