8153252: SA: Hotspot build on Windows fails if make/closed folder does not exist

Reviewed-by: dsamersoff, erikj

make/windows/makefiles/sa.make

@@ -44,9 +44,11 @@ HS_COMMON_SRC_REL = src
 HS_ALT_SRC_REL=src/closed
 HS_ALT_SRC = $(WorkSpace)/$(HS_ALT_SRC_REL)
 !ifndef HS_ALT_MAKE
+!if exist($(WorkSpace)/make/closed)
 HS_ALT_MAKE=$(WorkSpace)/make/closed
 !endif
 !endif
+!endif
 
 HS_COMMON_SRC = $(WorkSpace)/$(HS_COMMON_SRC_REL)