Add information about building with Cygwin Make 3.80.

nt/INSTALL

@@ -157,11 +157,11 @@
     cygwin compiled gmake 3.77:          fails[1, 5]   fails[2, 5]
     cygwin compiled make 3.78.1:         fails[5]      fails[2, 5]
     cygwin compiled make 3.79.1:         fails[3, 5]   fails[2?, 5]
-    cygwin compiled make 3.80:           fails?[6]     fails?[6]
-    cygwin compiled make 3.81:           fails         fails?[6]
+    cygwin compiled make 3.80:           okay[6]       fails?[7]
+    cygwin compiled make 3.81:           fails         fails?[7]
     mingw32 compiled make 3.79.1:        okay          okay
-    mingw32 compiled make 3.80:          okay          okay[6]
-    mingw32 compiled make 3.81:          okay          okay[7]
+    mingw32 compiled make 3.80:          okay          okay[7]
+    mingw32 compiled make 3.81:          okay          okay[8]
 
   Notes:
 
@@ -173,8 +173,10 @@
     [4] may fail on Windows 9X and Windows ME; if so, install Bash.
     [5] fails when building leim due to the use of cygwin style paths.
         May work if building emacs without leim.
-    [6] not recommended; please report if you try this combination.
-    [7] tested only on Windows XP.
+    [6] need to uncomment 3 lines in nt/gmake.defs that invoke `cygpath'
+    	(look for "cygpath" near line 85 of gmake.defs).
+    [7] not recommended; please report if you try this combination.
+    [8] tested only on Windows XP.
 
   Other compilers may work, but specific reports from people that have
   tried suggest that the Intel C compiler (for example) may produce an

nt/configure.bat

@@ -41,11 +41,11 @@ rem  mingw32/gcc-2.92.2 make (3.77):      okay          okay[4]
 rem  cygwin compiled gmake 3.77:          fails[1,5]    fails[2,5]
 rem  cygwin compiled gmake 3.78.1:        fails[5]      fails[2,5]
 rem  cygwin compiled gmake 3.79.1:        fails[3,5]    fails[2?,5]
-rem  cygwin compiled make 3.80:           fails?[6]     fails?[6]
-rem  cygwin compiled make 3.81:           fails         fails?[6]
+rem  cygwin compiled make 3.80:           okay[6]       fails?[7]
+rem  cygwin compiled make 3.81:           fails         fails?[7]
 rem  mingw32 compiled make 3.79.1:        okay          okay
-rem  mingw32 compiled make 3.80:          okay          okay?[6]
-rem  mingw32 compiled make 3.81:          okay          okay[7]
+rem  mingw32 compiled make 3.80:          okay          okay?[7]
+rem  mingw32 compiled make 3.81:          okay          okay[8]
 rem
 rem [1] doesn't cope with makefiles with DOS line endings, so must mount
 rem     emacs source with text!=binary.
@@ -55,8 +55,10 @@ rem     versions of cygwin.
 rem [4] may fail on Windows 9X and Windows ME; if so, install Bash.
 rem [5] fails when building leim due to the use of cygwin style paths.
 rem     May work if building emacs without leim.
-rem [6] not recommended; please report if you try this combination.
-rem [7] tested only on Windows XP.
+rem [6] need to uncomment 3 lines in nt/gmake.defs that invoke `cygpath';
+rem    	look for "cygpath" near line 85 of gmake.defs.
+rem [7] not recommended; please report if you try this combination.
+rem [8] tested only on Windows XP.
 rem
 
 if exist config.log del config.log