* CMakeLists.txt: Accommodate MingGW.

See https://github.com/StephanTLavavej/mingw-distro/issues/97.
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8dbca01..cbee5b3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -297,7 +297,7 @@
 endif ()
 
 # Create the configuration file
-if (UNIX)
+if (UNIX AND NOT WIN32)
   check_include_file("unistd.h" HAVE_UNISTD_H)
   check_include_file("fcntl.h" HAVE_FCNTL_H)
 
@@ -423,10 +423,10 @@
   src/winfonts/winfnt.c
 )
 
-if (UNIX)
-  list(APPEND BASE_SRCS "builds/unix/ftsystem.c")
-elseif (WIN32)
+if (WIN32)
   list(APPEND BASE_SRCS "builds/windows/ftsystem.c")
+elseif (UNIX)
+  list(APPEND BASE_SRCS "builds/unix/ftsystem.c")
 else ()
   list(APPEND BASE_SRCS "src/base/ftsystem.c")
 endif ()