fasthttp: make public on linux/windows

Author: medvednikov

vlib/fasthttp/fasthttp_linux.v

@@ -37,7 +37,7 @@ mut:
 	data   C.epoll_data_t
 }
 
-struct Server {
+pub struct Server {
 pub:
 	family                  net.AddrFamily = .ip6
 	port                    int            = 3000

vlib/fasthttp/fasthttp_windows.v

@@ -1,6 +1,6 @@
 module fasthttp
 
-struct Server {
+pub struct Server {
 pub:
 	port                    int = 3000
 	max_request_buffer_size int = 8192

vlib/v/gen/c/cheaders.v

@@ -480,10 +480,11 @@ typedef __builtin_va_list va_list;
 #ifdef __cplusplus
 extern "C" {
 #endif
-// mingw-w64 stdio.h declares these as static __mingw_ovr inline overrides.
-// Skip them under mingw to avoid static-after-extern conflicts when
-// thirdparty headers later include stdio.h.
-#if !defined(__MINGW32__) && !defined(__MINGW64__)
+// mingw-w64 stdio.h declares these as static __mingw_ovr inline overrides
+// when __USE_MINGW_ANSI_STDIO is on. Skip them under gcc+mingw to avoid
+// static-after-extern conflicts; clang+mingw needs them because it builds
+// with -Werror=implicit-function-declaration and does not hit the conflict.
+#if !((defined(__MINGW32__) || defined(__MINGW64__)) && !defined(__clang__))
 V_CRT_LINKAGE int V_CRT_CALL vfprintf(FILE *stream, const char *format, va_list ap);
 V_CRT_LINKAGE int V_CRT_CALL vsnprintf(char *str, size_t size, const char *format, va_list ap);
 V_CRT_LINKAGE int V_CRT_CALL fprintf(FILE *stream, const char *format, ...);

vlib/v/gen/c/cheaders_manual_stdlib_decls_test.v

@@ -73,7 +73,7 @@ fn test_msvc_windows_prelude_uses_msvc_crt_headers() {
 	assert generated_c.contains('#ifndef va_copy\n\t#define va_copy(dest, src) ((dest) = (src))\n#endif\n#ifndef _TRUNCATE'), generated_c
 	assert generated_c.contains('#if defined(_MSC_VER) && !defined(__clang__)\n\t#define V_CRT_LINKAGE __declspec(dllimport)\n\t#define V_CRT_CALL VCALLCONV(cdecl)\n#else\n\t#define V_CRT_LINKAGE\n\t#define V_CRT_CALL\n#endif'), generated_c
 	assert generated_c.contains('#if !defined(_MSC_VER) || defined(__clang__)\n#ifdef __cplusplus\nextern "C" {\n#endif\n'), generated_c
-	assert generated_c.contains('#if !defined(__MINGW32__) && !defined(__MINGW64__)\nV_CRT_LINKAGE int V_CRT_CALL vfprintf(FILE *stream, const char *format, va_list ap);'), generated_c
+	assert generated_c.contains('#if !((defined(__MINGW32__) || defined(__MINGW64__)) && !defined(__clang__))\nV_CRT_LINKAGE int V_CRT_CALL vfprintf(FILE *stream, const char *format, va_list ap);'), generated_c
 	assert generated_c.contains('V_CRT_LINKAGE int V_CRT_CALL _vscprintf(const char *format, va_list ap);'), generated_c
 	assert generated_c.contains('V_CRT_LINKAGE int V_CRT_CALL _vsnprintf_s(char *buffer, size_t size, size_t count, const char *format, va_list ap);'), generated_c
 	assert generated_c.contains('#include <windows.h>'), generated_c