Add 'check_tool' function to new ports mechanism

Fixes #1254.

repos/libports/ports/ncurses.hash

@@ -1 +1 @@
-d3a823f4ef6b45a184fb7c349d8efc2e55b0df96
+dd40dba9c711e4342a8dd66912034c0bc8fdb8d3

repos/libports/ports/ncurses.port

@@ -13,8 +13,8 @@ DIR_CONTENT(include/ncurses) := \
          nc_alloc.h nc_panel.h nc_tparm.h term_entry.h tic.h hashed_db.h \
          capdefaults.c)
 
-#$(call check_tool,sed)
-#$(call check_tool,mawk)
+$(call check_tool,sed)
+$(call check_tool,mawk)
 
 gen_inc   := curses.h ncurses_def.h ncurses_dll.h term.h \
              unctrl.h termcap.h parametrized.h hashsize.h \

repos/libports/ports/openssl.hash

@@ -1 +1 @@
-c43ce53cf840026e896b325c7ccded7506811f30
+d268763333f8e142ba331cfb5348e00e93bf3a96

repos/libports/ports/openssl.port

@@ -19,7 +19,7 @@ DIR_CONTENT(include/openssl) = $(shell find src/lib/openssl/include/openssl/ -na
 # Generate ASM codes
 #
 
-#$(call check_tool,sed)
+$(call check_tool,perl)
 
 gen_files := src/lib/openssl/x86_64/modexp512.s src/lib/openssl/x86_64/rc4_md5.s
 

tool/ports/mk/install.mk

@@ -20,6 +20,11 @@
 # XXX remove this line when the tool has stabilized
 STRICT_HASH ?= no
 
+#
+# Utility to check if a tool is installed
+#
+check_tool = $(if $(shell which $(1)),,$(error Need to have '$(1)' installed.))
+
 default:
 
 # repository that contains the port description, used to look up patch files
@@ -45,6 +50,10 @@ include $(PORT)
 #
 include $(GENODE_DIR)/tool/ports/mk/common.inc
 
+$(call check_tool,wget)
+$(call check_tool,patch)
+$(call check_tool, $(HASHSUM))
+
 #
 # Assertion for the presence of a LICENSE and VERSION declarations in the port
 # description