Improve build on Windows via llvm-mingw

windows/pci.c

@@ -0,0 +1,14 @@
+#include "pci.h"
+
+#include <stdio.h>
+#include <stdint.h>
+#include "../umka.h"
+
+char pci_path[UMKA_PATH_MAX] = ".";
+
+__attribute__((stdcall)) uint32_t pci_read(uint32_t bus, uint32_t dev,
+                                           uint32_t fun, uint32_t offset,
+                                           size_t len) {
+    printf("STUB: %s:%d", __FILE__, __LINE__);
+    return 0xffffffff;
+}

windows/pci.h

@@ -0,0 +1,8 @@
+#ifndef PCI_H_INCLUDED
+#define PCI_H_INCLUDED
+
+#include "../umka.h"
+
+extern char pci_path[UMKA_PATH_MAX];
+
+#endif  // PCI_H_INCLUDED

windows/thread.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+
+void reset_procmask(void) {
+    printf("STUB: %s:%d", __FILE__, __LINE__);
+}
+
+int get_fake_if(void *ctx) {
+    printf("STUB: %s:%d", __FILE__, __LINE__);
+    return 0;
+}