BuildSystem: Move all userpace libraries under the userspace directory

As the number of libraries is increasing, root directory starts to
expand. This adds better organization for libraries

userspace/libraries/LibC/strings.cpp

@@ -0,0 +1,30 @@
+#include <ctype.h>
+#include <strings.h>
+
+int ffs(int i)
+{
+	for (unsigned idx = 0; idx < sizeof(i) * 8; idx++)
+		if (i & (1 << idx))
+			return i + 1;
+	return 0;
+}
+
+int strcasecmp(const char* s1, const char* s2)
+{
+	const unsigned char* u1 = (unsigned char*)s1;
+	const unsigned char* u2 = (unsigned char*)s2;
+	for (; *u1 && *u2; u1++, u2++)
+		if (tolower(*u1) != tolower(*u2))
+			break;
+	return tolower(*u1) - tolower(*u2);
+}
+
+int strncasecmp(const char* s1, const char* s2, size_t n)
+{
+	const unsigned char* u1 = (unsigned char*)s1;
+	const unsigned char* u2 = (unsigned char*)s2;
+	for (; --n && *u1 && *u2; u1++, u2++)
+		if (tolower(*u1) != tolower(*u2))
+			break;
+	return tolower(*u1) - tolower(*u2);
+}