build: replace header checks with __has_include

See https://en.cppreference.com/w/cpp/preprocessor/include.

Author: fanquake

cmake/bitcoin-build-config.h.in

@@ -108,18 +108,6 @@
 /* Define to 1 if std::system or ::wsystem is available. */
 #cmakedefine HAVE_SYSTEM 1
 
-/* Define to 1 if you have the <sys/prctl.h> header file. */
-#cmakedefine HAVE_SYS_PRCTL_H 1
-
-/* Define to 1 if you have the <sys/resources.h> header file. */
-#cmakedefine HAVE_SYS_RESOURCES_H 1
-
-/* Define to 1 if you have the <sys/vmmeter.h> header file. */
-#cmakedefine HAVE_SYS_VMMETER_H 1
-
-/* Define to 1 if you have the <vm/vm_param.h> header file. */
-#cmakedefine HAVE_VM_VM_PARAM_H 1
-
 /* Define to the address where bug reports for this package should be sent. */
 #define CLIENT_BUGREPORT "@CLIENT_BUGREPORT@"
 

cmake/introspection.cmake

@@ -6,12 +6,6 @@ include(CheckCXXSourceCompiles)
 include(CheckCXXSymbolExists)
 include(CheckIncludeFileCXX)
 
-# The following HAVE_{HEADER}_H variables go to the bitcoin-build-config.h header.
-check_include_file_cxx(sys/prctl.h HAVE_SYS_PRCTL_H)
-check_include_file_cxx(sys/resources.h HAVE_SYS_RESOURCES_H)
-check_include_file_cxx(sys/vmmeter.h HAVE_SYS_VMMETER_H)
-check_include_file_cxx(vm/vm_param.h HAVE_VM_VM_PARAM_H)
-
 check_cxx_symbol_exists(O_CLOEXEC "fcntl.h" HAVE_O_CLOEXEC)
 check_cxx_symbol_exists(fdatasync "unistd.h" HAVE_FDATASYNC)
 check_cxx_symbol_exists(fork "unistd.h" HAVE_DECL_FORK)

src/randomenv.cpp

@@ -43,13 +43,13 @@
 #endif
 #ifdef HAVE_SYSCTL
 #include <sys/sysctl.h>
-#ifdef HAVE_VM_VM_PARAM_H
+#if __has_include(<vm/vm_param.h>)
 #include <vm/vm_param.h>
 #endif
-#ifdef HAVE_SYS_RESOURCES_H
+#if __has_include(<sys/resources.h>)
 #include <sys/resources.h>
 #endif
-#ifdef HAVE_SYS_VMMETER_H
+#if __has_include(<sys/vmmeter.h>)
 #include <sys/vmmeter.h>
 #endif
 #endif

src/util/threadnames.cpp

@@ -2,8 +2,6 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#include <bitcoin-build-config.h> // IWYU pragma: keep
-
 #include <cstring>
 #include <string>
 #include <thread>
@@ -16,7 +14,7 @@
 
 #include <util/threadnames.h>
 
-#ifdef HAVE_SYS_PRCTL_H
+#if __has_include(<sys/prctl.h>)
 #include <sys/prctl.h>
 #endif