Fix softIoc build with space in path to Base

Also improved error messages from makeInstallDir.pl.

src/softIoc/Makefile

@@ -33,7 +33,7 @@ softMain$(OBJ) : epicsInstallDir.h
 
 epicsInstallDir.h:
 	$(ECHO) "FINAL_LOCATION=$(FINAL_LOCATION)"
-	$(PERL) ../makeInstallDir.pl '$(FINAL_LOCATION)' > $@
+	$(PERL) ../makeInstallDir.pl "$(FINAL_LOCATION)" > $@
 
 clean::
 	@$(RM) epicsInstallDir.h

src/softIoc/makeInstallDir.pl

@@ -9,7 +9,8 @@ eval 'exec perl -S $0 ${1+"$@"}'  # -*- Mode: perl -*-
 
 use strict;
 
-die "Path to INSTALL_LOCATION missing\n" unless @ARGV == 1;
+die "$0: Argument missing, INSTALL_LOCATION\n" if @ARGV == 0;
+die "$0: Too many arguments, expecting one\n" unless @ARGV == 1;
 
 my $path = shift;