8350137: After JDK-8348975, Linux builds contain man pages for windows only tools

Backport-of: 53db57648a09c4c380064eea11fcdb680011d741

Author: nizarbenalla

make/Docs.gmk

@@ -680,7 +680,7 @@ ifeq ($(ENABLE_PANDOC), true)
 
   $(foreach m, $(ALL_MODULES), \
     $(eval MAN_$m := $(call ApplySpecFilter, $(filter %.md, $(call FindFiles, \
-          $(call FindModuleManDirs, $m))))) \
+          $(call FindModuleManDirsForDocs, $m))))) \
     $(if $(MAN_$m), \
       $(eval $(call SetupProcessMarkdown, MAN_TO_HTML_$m, \
         FILES := $(MAN_$m), \

make/common/Modules.gmk

@@ -92,7 +92,10 @@ SRC_SUBDIRS += share/classes
 
 SPEC_SUBDIRS += share/specs
 
-MAN_SUBDIRS += share/man windows/man
+MAN_SUBDIRS += share/man $(TARGET_OS)/man
+
+# The docs should include the sum of all man pages for all platforms
+MAN_DOCS_SUBDIRS += share/man windows/man
 
 # Find all module-info.java files for the current build target platform and
 # configuration.
@@ -158,6 +161,10 @@ FindModuleManDirs = \
     $(strip $(wildcard \
         $(foreach sub, $(MAN_SUBDIRS), $(addsuffix /$(strip $1)/$(sub), $(TOP_SRC_DIRS)))))
 
+FindModuleManDirsForDocs = \
+    $(strip $(wildcard \
+        $(foreach sub, $(MAN_DOCS_SUBDIRS), $(addsuffix /$(strip $1)/$(sub), $(TOP_SRC_DIRS)))))
+
 # Construct the complete module source path
 GetModuleSrcPath = \
     $(call PathList, \