freeimage: remove _WINDOWS_ definition

That macro indicates this is Windows OS, and breaks SLADE with wxWidgets
3.2.1

srcpkgs/freeimage/patches/no-windows.patch

@@ -0,0 +1,15 @@
+_WINDOWS_ is pre-defined macro definition for Windows OS
+Other libraries detect build on Windows by this macro
+Fix SLADE with wxWidgets 3.2
+Index: FreeImage/Source/FreeImage.h
+===================================================================
+--- FreeImage.orig/Source/FreeImage.h
++++ FreeImage/Source/FreeImage.h
+@@ -129,7 +129,6 @@ FI_STRUCT (FIMULTIBITMAP) { void *data;
+ #endif // __MINGW32__
+ 
+ #ifndef _WINDOWS_
+-#define _WINDOWS_
+ 
+ #ifndef FALSE
+ #define FALSE 0

srcpkgs/freeimage/template

@@ -1,7 +1,7 @@
 # Template file for 'freeimage'
 pkgname=freeimage
 version=3.18.0
-revision=3
+revision=4
 wrksrc=FreeImage
 build_style=gnu-makefile
 hostmakedepends="unzip"
@@ -57,10 +57,13 @@ freeimage-devel_package() {
 
 freeimage-plus-devel_package() {
 	short_desc+=" (plus) - development files"
-	depends="freeimage-plus>=${version}_${revision}"
+	# Only needs FreeImage.h from freeimage-devel
+	depends="freeimage-plus>=${version}_${revision}
+	 freeimage-devel>=${version}_${revision}"
 	pkg_install() {
 		DESTDIR="${DESTDIR/freeimage-/freeimage-plus-}"
 		vmove usr/include
+		rm -f "${PKGDESTDIR}/usr/include/FreeImage.h"
 		vmove usr/lib/libfreeimageplus.a
 		vmove usr/lib/libfreeimageplus.so
 #		vmkdir usr/lib