mingw: use ANSI or Unicode functions explicitly

For many Win32 functions, there actually exist two variants: one with
the `A` suffix that takes ANSI parameters (`char *` or `const char *`)
and one with the `W` suffix that takes Unicode parameters (`wchar_t *`
or `const wchar_t *`).

Let's be precise what we want to use.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

compat/mingw.c

@@ -1693,7 +1693,7 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaen
 	do_unset_environment_variables();
 
 	/* Determine whether or not we are associated to a console */
-	cons = CreateFile("CONOUT$", GENERIC_WRITE,
+	cons = CreateFileA("CONOUT$", GENERIC_WRITE,
 			FILE_SHARE_WRITE, NULL, OPEN_EXISTING,
 			FILE_ATTRIBUTE_NORMAL, NULL);
 	if (cons == INVALID_HANDLE_VALUE) {
@@ -2358,7 +2358,7 @@ struct passwd *getpwuid(int uid)
 		return p;
 
 	len = sizeof(user_name);
-	if (!GetUserName(user_name, &len)) {
+	if (!GetUserNameA(user_name, &len)) {
 		initialized = 1;
 		return NULL;
 	}

compat/poll/poll.c

@@ -150,7 +150,7 @@ win32_compute_revents (HANDLE h, int *p_sought)
       if (!once_only)
 	{
 	  NtQueryInformationFile = (PNtQueryInformationFile)
-	    GetProcAddress (GetModuleHandle ("ntdll.dll"),
+	    GetProcAddress (GetModuleHandleA ("ntdll.dll"),
 			    "NtQueryInformationFile");
 	  once_only = TRUE;
 	}

compat/winansi.c

@@ -629,12 +629,12 @@ void winansi_init(void)
 
 	/* create a named pipe to communicate with the console thread */
 	xsnprintf(name, sizeof(name), "\\\\.\\pipe\\winansi%lu", GetCurrentProcessId());
-	hwrite = CreateNamedPipe(name, PIPE_ACCESS_OUTBOUND,
+	hwrite = CreateNamedPipeA(name, PIPE_ACCESS_OUTBOUND,
 		PIPE_TYPE_BYTE | PIPE_WAIT, 1, BUFFER_SIZE, 0, 0, NULL);
 	if (hwrite == INVALID_HANDLE_VALUE)
 		die_lasterr("CreateNamedPipe failed");
 
-	hread = CreateFile(name, GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL);
+	hread = CreateFileA(name, GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL);
 	if (hread == INVALID_HANDLE_VALUE)
 		die_lasterr("CreateFile for named pipe failed");