Fix "/bin/sh:" errors when building without LLVM

In GNUmakefile.llvm, several variables are unconditionally populated
by expanding $(LLVMVER) and $(LLVM_CONFIG) inside shell commands.
However, when LLVM is not present, both those variables are empty,
meaning that the shell commands end up malformed and emit harmless, but
noisy, errors like this one:

  /bin/sh: --: invalid option
  Usage:	/bin/sh [GNU long option] [option] ...
  	/bin/sh [GNU long option] [option] script-file ...
  GNU long options:
  	--debug
  	--debugger
  	--dump-po-strings
  	--dump-strings
  	--help
  	--init-file
  	--login
  	--noediting
  	--noprofile
  	--norc
  	--posix
  	--pretty-print
  	--rcfile
  	--rpm-requires
  	--restricted
  	--verbose
  	--version
  Shell options:
  	-ilrsD or -c command or -O shopt_option		(invocation only)
  	-abefhkmnptuvxBCHP or -o option
  /bin/sh: line 1: test: -gt: unary operator expected
  /bin/sh: line 1: test: -lt: unary operator expected
  /bin/sh: line 1: test: -ge: unary operator expected
  /bin/sh: line 1: test: -ge: unary operator expected

Fix the problem by only populating the "downstream" variables if the
upstream ones have values.

0 files changed, 0 insertions, 0 deletions