Indent rule commands consistently with a TAB.

[Ralf Wildenhues]

I noticed that some of our rules had commands indented by 8 spaces
rather than a TAB.  I only recently learned from John Calcote that
POSIX doesn't even require indentation at all for the continuation
lines of rule commands; but I won't change this practice now, given
that it's been done throughout in Automake.  We haven't found a make
implementation that requires it, though.

Pushed to master, added you to THANKS, will backport the relevant parts
to branch-1-10.

Cheers, and thanks!
Ralf

    Indent rule commands consistently with a TAB.
    
    * lib/am/check.am ($(TEST_SUITE_LOG)): Consistently use TAB, not
    spaces, for indentation of commands, even if indentation may not
    be needed at all.
    * lib/am/texinfos.am (install-info-am): Likewise.
    * THANKS: Update.
    Prompted by report from John Calcote.

diff --git a/lib/am/check.am b/lib/am/check.am
index 74f0563..6653f7b 100644
--- a/lib/am/check.am
+++ b/lib/am/check.am
@@ -177,7 +177,7 @@ $(TEST_SUITE_LOG): $(TEST_LOGS)
            msg="$$msg ($$xpass unexpected $$xpasses).  ";              \
            exit=false;;                                                \
          *)                                                            \
-            echo >&2 "incorrect case"; exit 4;;                                
\
+           echo >&2 "incorrect case"; exit 4;;                         \
        esac;                                                           \
        if test "$$skip" -ne 0; then                                    \
          if test "$$skip" -eq 1; then                                  \
diff --git a/lib/am/texinfos.am b/lib/am/texinfos.am
index 5dda4ab..8d0eb87 100644
--- a/lib/am/texinfos.am
+++ b/lib/am/texinfos.am
@@ -198,7 +198,7 @@ install-info-am: $(INFO_DEPS)
 ## `foo' becomes `foo.i' too.
          file_i=`echo "$$file" | sed 's|\.info$$||;s|$$|.i|'`; \
          for ifile in $$d/$$file $$d/$$file-[0-9] $$d/$$file-[0-9][0-9] \
-                       $$d/$$file_i[0-9] $$d/$$file_i[0-9][0-9] ; do \
+                      $$d/$$file_i[0-9] $$d/$$file_i[0-9][0-9] ; do \
            if test -f $$ifile; then \
              echo "$$ifile"; \
            else : ; fi; \