Remove the _INSTALL_IN support in the build system

It doesn't seem to do anything that _INSTALL and _INSTALL_INPLACE
can't do.

driver/split/ghc.mk

@@ -13,7 +13,8 @@
 driver/split_PERL_SRC  = ghc-split.lprl
 driver/split_dist_PROG = $(GHC_SPLIT_PGM)
 driver/split_dist_TOPDIR = YES
-driver/split_dist_INSTALL_IN = $(DESTDIR)$(topdir)
+driver/split_dist_INSTALL = YES
+driver/split_dist_INSTALL_INPLACE = YES
 
 $(eval $(call build-perl,driver/split,dist))
 

rules/build-perl.mk

@@ -54,16 +54,6 @@ $$($1_$2_INPLACE): $1/$2/$$($1_$2_PROG) | $$$$(dir $$$$@)/.
 	"$$(CP)" $$< $$@
 	$$(EXECUTABLE_FILE) $$@
 
-ifneq "$$($1_$2_INSTALL_IN)" ""
-BINDIST_PERL_SOURCES += $1/$2/$$($1_$2_PROG).prl
-
-install: install_$1_$2
-
-.PHONY: install_$1_$2
-install_$1_$2: $1/$2/$$($1_$2_PROG)
-	$$(call INSTALL_DIR,"$$($1_$2_INSTALL_IN)")
-	$$(call INSTALL_SCRIPT,$$(INSTALL_OPTS),$$<,"$$($1_$2_INSTALL_IN)")
-endif
 endif
 
 $(call profEnd, build-perl($1,$2))