Allow programs to have custom names

Logic modeled after that for libraries.

mk/programs.mk

@@ -3,6 +3,9 @@ programs-list :=
 # Build a program with symbolic name $(1).  The program is defined by
 # various variables prefixed by ‘$(1)_’:
 #
+# - $(1)_NAME: the name of the program (e.g. ‘foo’); defaults to
+#   $(1).
+#
 # - $(1)_DIR: the directory where the (non-installed) program will be
 #   placed.
 #
@@ -23,11 +26,12 @@ programs-list :=
 # - $(1)_INSTALL_DIR: the directory where the program will be
 #   installed; defaults to $(bindir).
 define build-program
+  $(1)_NAME ?= $(1)
   _d := $(buildprefix)$$($(1)_DIR)
   _srcs := $$(sort $$(foreach src, $$($(1)_SOURCES), $$(src)))
   $(1)_OBJS := $$(addprefix $(buildprefix), $$(addsuffix .o, $$(basename $$(_srcs))))
   _libs := $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_PATH))
-  $(1)_PATH := $$(_d)/$(1)
+  $(1)_PATH := $$(_d)/$$($(1)_NAME)
 
   $$(eval $$(call create-dir, $$(_d)))
 
@@ -38,7 +42,7 @@ define build-program
 
   ifdef $(1)_INSTALL_DIR
 
-    $(1)_INSTALL_PATH := $$($(1)_INSTALL_DIR)/$(1)
+    $(1)_INSTALL_PATH := $$($(1)_INSTALL_DIR)/$$($(1)_NAME)
 
     $$(eval $$(call create-dir, $$($(1)_INSTALL_DIR)))