Fix two warnings on MinGW

src/asm/section.cpp

@@ -934,8 +934,14 @@ bool sect_BinaryFile(std::string const &name, uint32_t startPos) {
 	Defer closeFile{[&] { fclose(file); }};
 
 	if (fseek(file, 0, SEEK_END) == 0) {
-		if (startPos > ftell(file)) {
-			error("Specified start position is greater than length of file \"%s\"", name.c_str());
+		if (unsigned long fsize = ftell(file);
+		    startPos > fsize) { // `ftell` cannot fail here, since `fseek` succeeded.
+			error(
+			    "Specified start position (%" PRIu32 ") is greater than length of \"%s\" (%lu)",
+			    startPos,
+			    name.c_str(),
+			    fsize
+			);
 			return false;
 		}
 		// The file is seekable; skip to the specified start position
@@ -989,8 +995,14 @@ bool sect_BinaryFileSlice(std::string const &name, uint32_t startPos, uint32_t l
 	Defer closeFile{[&] { fclose(file); }};
 
 	if (fseek(file, 0, SEEK_END) == 0) {
-		if (long fsize = ftell(file); startPos > fsize) {
-			error("Specified start position is greater than length of file \"%s\"", name.c_str());
+		if (unsigned long fsize = ftell(file);
+		    startPos > fsize) { // `ftell` cannot fail here, since `fseek` succeeded.
+			error(
+			    "Specified start position (%" PRIu32 ") is greater than length of \"%s\" (%lu)",
+			    startPos,
+			    name.c_str(),
+			    fsize
+			);
 			return false;
 		} else if (startPos + length > fsize) {
 			error(

test/asm/incbin-start-bad.err

@@ -1,5 +1,5 @@
-error: Specified start position is greater than length of file "data.bin"
+error: Specified start position (999) is greater than length of "data.bin" (123)
     at incbin-start-bad.asm(3)
-error: Specified start position is greater than length of file "data.bin"
+error: Specified start position (999) is greater than length of "data.bin" (123)
     at incbin-start-bad.asm(4)
 Assembly aborted with 2 errors

test/gfx/rgbgfx_test.cpp

@@ -320,7 +320,7 @@ static char *execProg(char const *name, char * const *argv) {
 		        nullptr,
 		        errnum,
 		        0,
-		        (LPTSTR)&buf,
+		        reinterpret_cast<LPTSTR>(&buf),
 		        0,
 		        nullptr
 		    )
@@ -341,7 +341,8 @@ static char *execProg(char const *name, char * const *argv) {
 
 	STARTUPINFOA startupInfo;
 	GetStartupInfoA(&startupInfo);
-	STARTUPINFOA childStartupInfo = {sizeof(startupInfo)};
+	STARTUPINFOA childStartupInfo = {};
+	childStartupInfo.cb = sizeof(startupInfo);
 
 	PROCESS_INFORMATION child;
 	if (CreateProcessA(