Merge branch 'tb/make-indent-conditional-with-non-spaces'

Adjust to an upcoming changes to GNU make that breaks our Makefiles.

* tb/make-indent-conditional-with-non-spaces:
  Makefile(s): do not enforce "all indents must be done with tab"
  Makefile(s): avoid recipe prefix in conditional statements

diff --cc Makefile
Simple merge

diff --cc config.mak.uname
index fcf3e2d785a04d765a495b67e24515755ef81c8e,cc5660e9251e89772a11b3cf2bbcbd1a127e22a8..a7607a567610a74bfae56214fc5787f063916ab3
--- 1/config.mak.uname
--- 2/config.mak.uname
+++ b/config.mak.uname
@@@ -637,22 -638,10 +637,22 @@@ ifeq ($(uname_S),NONSTOP_KERNEL
        SANE_TOOL_PATH = /usr/coreutils/bin:/usr/local/bin
        SHELL_PATH = /usr/coreutils/bin/bash
  endif
 +ifeq ($(uname_S),OS/390)
 +      NO_SYS_POLL_H = YesPlease
 +      NO_STRCASESTR = YesPlease
 +      NO_REGEX = YesPlease
 +      NO_MMAP = YesPlease
 +      NO_NSEC = YesPlease
 +      NO_STRLCPY = YesPlease
 +      NO_MEMMEM = YesPlease
 +      NO_GECOS_IN_PWENT = YesPlease
 +      HAVE_STRINGS_H = YesPlease
 +      NEEDS_MODE_TRANSLATION = YesPlease
 +endif
  ifeq ($(uname_S),MINGW)
-       ifeq ($(shell expr "$(uname_R)" : '1\.'),2)
+         ifeq ($(shell expr "$(uname_R)" : '1\.'),2)
                $(error "Building with MSys is no longer supported")
-       endif
+         endif
        pathsep = ;
        HAVE_ALLOCA_H = YesPlease
        NO_PREAD = YesPlease