math/readstat: fix build with clang15

.. continuing story of missing prototypes.

math/readstat/Makefile

@@ -1,6 +1,6 @@
 PORTNAME=	readstat
 DISTVERSION=	1.1.8
-PORTREVISION=	3
+PORTREVISION=	4
 CATEGORIES=	math kde
 MASTER_SITES=	https://github.com/WizardMac/ReadStat/releases/download/v${DISTVERSION}/
 

math/readstat/files/patch-src_readstat__writer.c

@@ -0,0 +1,11 @@
+--- src/readstat_writer.c.orig	2023-05-02 13:36:19 UTC
++++ src/readstat_writer.c
+@@ -35,7 +35,7 @@ readstat_string_ref_t *readstat_string_ref_init(const 
+     return ref;
+ }
+
+-readstat_writer_t *readstat_writer_init() {
++readstat_writer_t *readstat_writer_init(void) {
+     readstat_writer_t *writer = calloc(1, sizeof(readstat_writer_t));
+
+     writer->variables = calloc(VARIABLES_INITIAL_CAPACITY, sizeof(readstat_variable_t *));

math/readstat/files/patch-src_sas_readstat__sas.c

@@ -0,0 +1,11 @@
+--- src/sas/readstat_sas.c.orig	2023-05-02 13:35:12 UTC
++++ src/sas/readstat_sas.c
+@@ -120,7 +120,7 @@ static readstat_charset_entry_t _charset_table[] = { 
+     { .code = 248,   .name = "SHIFT_JISX0213" },
+ };
+
+-static time_t sas_epoch() {
++static time_t sas_epoch(void) {
+     return - 3653 * 86400; // seconds between 01-01-1960 and 01-01-1970
+ }
+

math/readstat/files/patch-src_sas_readstat__xport__read.c

@@ -0,0 +1,11 @@
+--- src/sas/readstat_xport_read.c.orig	2023-05-02 13:35:52 UTC
++++ src/sas/readstat_xport_read.c
+@@ -45,7 +45,7 @@ static readstat_error_t xport_update_progress(xport_ct
+     return io->update(ctx->file_size, ctx->handle.progress, ctx->user_ctx, io->io_ctx);
+ }
+
+-static xport_ctx_t *xport_ctx_init() {
++static xport_ctx_t *xport_ctx_init(void) {
+     xport_ctx_t *ctx = calloc(1, sizeof(xport_ctx_t));
+     return ctx;
+ }