LibC: Fix errno to work with shared libraries

userspace/libraries/LibC/CMakeLists.txt

@@ -4,6 +4,7 @@ set(LIBC_SOURCES
 	ctype.cpp
 	dirent.cpp
 	dlfcn.cpp
+	errno.cpp
 	fcntl.cpp
 	ftw.cpp
 	grp.cpp

userspace/libraries/LibC/errno.cpp

@@ -0,0 +1,8 @@
+#include <errno.h>
+
+static int s_errno = 0;
+
+int* __errno_location()
+{
+	return &s_errno;
+}

userspace/libraries/LibC/include/errno.h

@@ -93,9 +93,9 @@ __BEGIN_DECLS
 
 #define EUNKNOWN		0xFF
 
-#define errno __errno
+#define errno (*__errno_location())
 
-extern int __errno;
+int* __errno_location(void);
 
 __END_DECLS
 

userspace/libraries/LibC/string.cpp

@@ -8,8 +8,6 @@
 #include <stdlib.h>
 #include <string.h>
 
-int errno = 0;
-
 void* memccpy(void* __restrict s1, const void* __restrict s2, int c, size_t n)
 {
 	unsigned char* dst = static_cast<unsigned char*>(s1);