8215635: Pandoc check in Docs.gmk does not work on Windows

Reviewed-by: tbell, ihse

make/Docs.gmk

@@ -517,7 +517,7 @@ $(foreach m, $(ALL_MODULES), \
   ) \
 )
 
-ifneq ($(PANDOC), )
+ifeq ($(ENABLE_PANDOC), true)
   # For all markdown files in $module/share/specs directories, convert them to
   # html, if we have pandoc (otherwise we'll just skip this).
 

make/autoconf/basics.m4

@@ -610,7 +610,14 @@ AC_DEFUN_ONCE([BASIC_SETUP_FUNDAMENTAL_TOOLS],
   BASIC_PATH_PROGS(DF, df)
   BASIC_PATH_PROGS(CPIO, [cpio bsdcpio])
   BASIC_PATH_PROGS(NICE, nice)
+
   BASIC_PATH_PROGS(PANDOC, pandoc)
+  if test -n "$PANDOC"; then
+    ENABLE_PANDOC="true"
+  else
+    ENABLE_PANDOC="false"
+  fi
+  AC_SUBST(ENABLE_PANDOC)
 ])
 
 ###############################################################################

make/autoconf/spec.gmk.in

@@ -761,6 +761,7 @@ MSVCR_DLL:=@MSVCR_DLL@
 MSVCP_DLL:=@MSVCP_DLL@
 UCRT_DLL_DIR:=@UCRT_DLL_DIR@
 STLPORT_LIB:=@STLPORT_LIB@
+ENABLE_PANDOC:=@ENABLE_PANDOC@
 
 ####################################################
 #

make/launcher/LauncherCommon.gmk

@@ -203,7 +203,7 @@ ifeq ($(OPENJDK_TARGET_OS_TYPE), unix)
 
   ifneq ($(MAN_FILES_MD), )
     # If we got markdown files, ignore the troff files
-    ifeq ($(PANDOC), )
+    ifeq ($(ENABLE_PANDOC), false)
       $(info Warning: pandoc not found. Not generating man pages)
     else
       # Create dynamic man pages from markdown using pandoc. We need