[glibc] Makeconfig: Use $(error ...) to output error message

[Florian Weimer <fw@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=9207e30d3f070712df6c4175547094be112454d2

commit 9207e30d3f070712df6c4175547094be112454d2
Author: Simon Marchi <simon.marchi@efficios.com>
Date:   Wed Apr 29 11:24:41 2020 +0200

    Makeconfig: Use $(error ...) to output error message
    
    Being not familiar with the glibc repository, I typed "make" inside some
    subdirectory that has a Makefile, and was met with:
    
        $ make
        ../Makeconfig:42: *** missing separator.  Stop.
    
    At Makeconfig:42, we have:
    
        objdir must be defined by the build-directory Makefile.
    
    Change that to use $(error ...), which I guess was the original
    intention.  The result is:
    
        $ make
        ../Makeconfig:42: *** objdir must be defined by the build-directory Makefile.  Stop.

Diff:
---
 Makeconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makeconfig b/Makeconfig
index ac567caddc..dfda418aac 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -39,7 +39,7 @@ objpfx := $(patsubst %//,%/,$(objdir)/$(subdir)/)
 common-objpfx = $(objdir)/
 common-objdir = $(objdir)
 else
-objdir must be defined by the build-directory Makefile.
+$(error objdir must be defined by the build-directory Makefile)
 endif
 
 # Root of the sysdeps tree.