Use __has_include() instead of check_include_file()

Allows removing some CMake checks config-kwin.h contents. This is
supported by all compilers and required for C++17. While touching those
lines I also cleaned up an unnecessary HAVE_UNISTD_H check (glibc always
has it and and incorrect use of HAVE_SYS_PROCCTL_H.

CMakeLists.txt

@@ -355,10 +355,6 @@ set(HAVE_X11_XCB ${X11_XCB_FOUND})
 include(CheckIncludeFile)
 include(CheckIncludeFiles)
 include(CheckSymbolExists)
-check_include_files(unistd.h HAVE_UNISTD_H)
-check_include_files(malloc.h HAVE_MALLOC_H)
-
-check_include_file("sys/sysmacros.h" HAVE_SYS_SYSMACROS_H)
 
 check_symbol_exists(SCHED_RESET_ON_FORK "sched.h" HAVE_SCHED_RESET_ON_FORK)
 add_feature_info("SCHED_RESET_ON_FORK"

src/config-kwin.h.cmake

@@ -18,7 +18,6 @@
 #cmakedefine01 HAVE_X11_XINPUT
 #cmakedefine01 HAVE_GBM_BO_GET_FD_FOR_PLANE
 #cmakedefine01 HAVE_WAYLAND_EGL
-#cmakedefine01 HAVE_SYS_SYSMACROS_H
 #cmakedefine01 HAVE_BREEZE_DECO
 #cmakedefine01 HAVE_LIBCAP
 #cmakedefine01 HAVE_SCHED_RESET_ON_FORK
@@ -27,12 +26,6 @@
 #define BREEZE_KDECORATION_PLUGIN_ID "${BREEZE_KDECORATION_PLUGIN_ID}"
 #endif
 
-/* Define to 1 if you have the <unistd.h> header file. */
-#cmakedefine HAVE_UNISTD_H 1
-
-/* Define to 1 if you have the <malloc.h> header file. */
-#cmakedefine HAVE_MALLOC_H 1
-
 #cmakedefine XCB_ICCCM_FOUND 1
 #ifndef XCB_ICCCM_FOUND
 #define XCB_ICCCM_WM_STATE_WITHDRAWN 0

src/main.cpp

@@ -47,13 +47,13 @@
 #include <QLibraryInfo>
 
 // system
-#ifdef HAVE_UNISTD_H
+#if __has_include(<unistd.h>)
 #include <unistd.h>
-#endif // HAVE_UNISTD_H
+#endif
 
-#ifdef HAVE_MALLOC_H
+#ifdef __has_include(<malloc.h>)
 #include <malloc.h>
-#endif // HAVE_MALLOC_H
+#endif
 
 // xcb
 #include <xcb/damage.h>
@@ -255,11 +255,7 @@ void Application::setupMalloc()
     // due to fragmentation especially if we use the raster graphicssystem. On the
     // otherside if the threshold is too low, free() starts to permanently ask the kernel
     // about shrinking the heap.
-#ifdef HAVE_UNISTD_H
     const int pagesize = sysconf(_SC_PAGESIZE);
-#else
-    const int pagesize = 4*1024;
-#endif // HAVE_UNISTD_H
     mallopt(M_TRIM_THRESHOLD, 5*pagesize);
 #endif // M_TRIM_THRESHOLD
 }

src/main_x11.cpp

@@ -42,9 +42,9 @@
 #include <QtDBus>
 
 // system
-#ifdef HAVE_UNISTD_H
+#if __has_include(<unistd.h>)
 #include <unistd.h>
-#endif // HAVE_UNISTD_H
+#endif
 #include <iostream>
 
 Q_LOGGING_CATEGORY(KWIN_CORE, "kwin_core", QtWarningMsg)

src/session_consolekit.cpp

@@ -21,7 +21,7 @@
 #include <sys/stat.h>
 #include <unistd.h>
 
-#if HAVE_SYS_SYSMACROS_H
+#if __has_include(<sys/sysmacros.h>)
 #include <sys/sysmacros.h>
 #endif
 

src/session_logind.cpp

@@ -21,7 +21,7 @@
 #include <sys/stat.h>
 #include <unistd.h>
 
-#if HAVE_SYS_SYSMACROS_H
+#if __has_include(<sys/sysmacros.h>)
 #include <sys/sysmacros.h>
 #endif
 

src/xwl/xwayland.cpp

@@ -43,10 +43,7 @@
 #include <QtConcurrentRun>
 
 // system
-#ifdef HAVE_UNISTD_H
-#include <unistd.h>
-#endif
-#if HAVE_SYS_PROCCTL_H
+#if __has_include(<unistd.h>)
 #include <unistd.h>
 #endif