GNU Make 3.81 compatibility

3.81 doesn't understand the ‘define foo =’ syntax, which was added in
3.82.  So use ‘define foo’ instead.

mk/install.mk

@@ -1,6 +1,6 @@
 # Add a rule for creating $(1) as a directory.  This template may be
 # called multiple times for the same directory.
-define create-dir =
+define create-dir
   ifndef $(1)_SEEN
     $(1)_SEEN = 1
     $(1):
@@ -11,7 +11,7 @@ endef
 
 # Add a rule for installing file $(1) as file $(2) with mode $(3).
 # The directory containing $(2) will be created automatically.
-define install-file-as =
+define install-file-as
 
   install: $(2)
 
@@ -25,23 +25,23 @@ endef
 
 # Add a rule for installing file $(1) in directory $(2) with mode
 # $(3).  The directory will be created automatically.
-define install-file-in =
+define install-file-in
   $$(eval $$(call install-file-as,$(1),$(2)/$$(notdir $(1)),$(3)))
 endef
 
 
-define install-program-in =
+define install-program-in
   $$(eval $$(call install-file-in,$(1),$(2),0755))
 endef
 
 
-define install-data-in =
+define install-data-in
   $$(eval $$(call install-file-in,$(1),$(2),0644))
 endef
 
 
 # Install a symlink from $(2) to $(1).  Note that $(1) need not exist.
-define install-symlink =
+define install-symlink
 
   install: $(2)