Make clearer distinctions between OS includes

Author: Bill-hbrhbr

src/ystdlib/wrapped_facade_headers/bits/types/clock_t.h

@@ -3,9 +3,9 @@
 
 // clang-format off
 // IWYU pragma: begin_exports
+#if defined(__linux__)
 #include <bits/types/clock_t.h>
-
-#if defined(__APPLE__)
+#elif defined(__APPLE__)
 #include <sys/_types/_clock_t.h>
 #endif
 // IWYU pragma: end_exports

src/ystdlib/wrapped_facade_headers/bits/types/clockid_t.h

@@ -3,12 +3,12 @@
 
 // clang-format off
 // IWYU pragma: begin_exports
+#if defined(__linux__)
 #include <bits/types/clockid_t.h>
-
-#if defined(__APPLE__)
+#elif defined(__APPLE__)
 #include <_time.h>
 #endif
 // IWYU pragma: end_exports
 // clang-format on
 
-#endif  // YSTDLIB_WRAPPED_FACADE_HEADERS_BITS_TYPES_CLOCK_T_HPP
+#endif  // YSTDLIB_WRAPPED_FACADE_HEADERS_BITS_TYPES_CLOCKID_T_HPP

src/ystdlib/wrapped_facade_headers/bits/types/time_t.h

@@ -3,9 +3,9 @@
 
 // clang-format off
 // IWYU pragma: begin_exports
+#if defined(__linux__)
 #include <bits/types/time_t.h>
-
-#if defined(__APPLE__)
+#elif defined(__APPLE__)
 #include <sys/_types/_time_t.h>
 #endif
 // IWYU pragma: end_exports

src/ystdlib/wrapped_facade_headers/sys/types.h

@@ -1,8 +1,11 @@
+#ifndef YSTDLIB_WRAPPED_FACADE_HEADERS_SYS_TYPES_HPP
+#define YSTDLIB_WRAPPED_FACADE_HEADERS_SYS_TYPES_HPP
+
 // clang-format off
 // IWYU pragma: begin_exports
+#if defined(__linux__)
 #include <sys/types.h>
-
-#if defined(__APPLE__)
+#elif defined(__APPLE__)
 #include <sys/_types/_u_char.h>
 #include <sys/_types/_u_short.h>
 #include <sys/_types/_u_int.h>
@@ -26,3 +29,5 @@
 #endif
 // IWYU pragma: end_exports
 // clang-format on
+
+#endif  // YSTDLIB_WRAPPED_FACADE_HEADERS_SYS_TYPES_HPP