Add a check for 'windres' to configure.ac,

if Windows GUI or Console

configure.ac

@@ -609,6 +609,22 @@ case $host_os in
 esac
 AM_CONDITIONAL([WINCONSOLE], [test "x$has_winconsole" = xyes])
 
+if test "x$has_winconsole" = xyes; then
+    AC_CHECK_PROGS([WINRES], [windres windres.exe], [no])
+    if test "x$WINRES" = xno; then
+        AC_MSG_WARN([If you want adding the icon you should install windres])
+    fi
+fi
+
+if test "x$with_wingui" = xyes; then
+    AC_CHECK_PROGS([WINRES], [windres windres.exe], [no])
+    if test "x$WINRES" = xno; then
+        AC_MSG_WARN([If you want adding the icon you should install windres])
+    fi
+fi
+
+AM_CONDITIONAL([WINRESOURCE], [test "x$WINRES" = xwindres])
+
 case $with_wingui in
     yes )
         AC_DEFINE([X_DISPLAY_MISSING])

src/Makefile.am

@@ -103,11 +103,7 @@ DYNAMIC_DEVICELIBS =					\
 ## Build ngspice first:
 
 ## compile the icon:
-if WINGUI
-ngicon.o: ngicon.rc
-	windres $(srcdir)/ngicon.rc -O coff -o ngicon.o
-endif
-if WINCONSOLE
+if WINRESOURCE
 ngicon.o: ngicon.rc
 	windres $(srcdir)/ngicon.rc -O coff -o ngicon.o
 endif
@@ -202,11 +198,7 @@ ngspice_LDADD += frontend/help/libhlp.la
 endif
 endif
 
-if WINGUI
-ngspice_LDADD += ngicon.o
-endif
-
-if WINCONSOLE
+if WINRESOURCE
 ngspice_LDADD += ngicon.o
 endif