Fix mmap() C API detection on macOS

The CheckFmapFeatures module is failing because HAVE_SYS_STAT_H and
HAVE_SYS_TYPES_H are not defined within the check_c_source_compiles
environment.

This commit adds them in the same way as is done for CheckFDPassing
module.

cmake/CheckFmapFeatures.cmake

@@ -4,6 +4,15 @@ include(CheckSymbolExists)
 include(CheckFunctionExists)
 include(CheckCSourceCompiles)
 
+# Extra -D Compile Definitions for check_c_source_compiles()
+set(CMAKE_REQUIRED_DEFINITIONS "")
+if(HAVE_SYS_TYPES_H)
+    set(CMAKE_REQUIRED_DEFINITIONS "${CMAKE_REQUIRED_DEFINITIONS};-DHAVE_SYS_TYPES_H=1")
+endif()
+if(HAVE_SYS_STAT_H)
+    set(CMAKE_REQUIRED_DEFINITIONS "${CMAKE_REQUIRED_DEFINITIONS};-DHAVE_SYS_STAT_H=1")
+endif()
+
 # Check for mmap() support, required for HAVE_MPOOL.
 #
 # checks for private fixed mappings, we don't need fixed mappings,