Haiku: Add support for RESCAN

Haiku also uses the GNU toolchain and therefore should support this
feature.

Help/variable/include/LINK_GROUP_PREDEFINED_FEATURES.rst

@@ -20,3 +20,7 @@
   This feature is available when using toolchains that target Linux, BSD, and
   SunOS.  It can also be used when targeting Windows platforms if the GNU
   toolchain is used.
+
+  .. versionadded:: 4.4
+    ``RESCAN`` is additionally available when using toolchains targeting
+    Haiku.

Modules/Platform/Haiku.cmake

@@ -8,6 +8,12 @@ set(CMAKE_SHARED_LIBRARY_RPATH_LINK_C_FLAG "-Wl,-rpath-link,")
 set(CMAKE_SHARED_LIBRARY_SONAME_C_FLAG "-Wl,-soname,")
 set(CMAKE_EXE_EXPORTS_C_FLAG "-Wl,--export-dynamic")
 
+# Features for LINK_GROUP generator expression
+## RESCAN: request the linker to rescan static libraries until there is
+## no pending undefined symbols
+set(CMAKE_LINK_GROUP_USING_RESCAN "LINKER:--start-group" "LINKER:--end-group")
+set(CMAKE_LINK_GROUP_USING_RESCAN_SUPPORTED TRUE)
+
 # Determine, if the C or C++ compiler is configured for a secondary
 # architecture. If so, that will change the search paths we set below. We check
 # whether the compiler's library search paths contain a

Tests/RunCMake/target_link_libraries-LINK_GROUP/RunCMakeTest.cmake

@@ -63,7 +63,7 @@ if ((RunCMake_GENERATOR MATCHES "Makefiles|Ninja|Xcode"
 endif()
 
 # Feature RESCAN
-if (CMAKE_SYSTEM_NAME MATCHES "Linux|BSD"
+if (CMAKE_SYSTEM_NAME MATCHES "Linux|BSD|Haiku"
     OR (CMAKE_SYSTEM_NAME STREQUAL "SunOS" AND (NOT CMAKE_C_COMPILER_ID STREQUAL "SunPro" OR CMAKE_C_COMPILER_VERSION VERSION_GREATER "5.9"))
     OR (WIN32 AND CMAKE_C_COMPILER_ID STREQUAL "GNU"))
   run_cmake(rescan)