Makefile.am: Fix build without pandoc

When building from a tarball, pre-created man pages are preset. Yet `make
clean` clobbers them, leaving their target directory intact. Therefore, the
next configure call will try to build man pages even if pandoc isn't
available.

Fix this by cleaning the man pages only if they can be recreated by the
presence of pandoc.

Fixes tpm2-software#284

Signed-off-by: Moritz Barsnick <moritz.barsnick@chargebyte.com>

Author: barsnick

Makefile.am

@@ -217,8 +217,10 @@ EXTRA_DIST += \
     man/tpm2tss_ecc_genkey.3.md \
     man/tpm2tss_ecc_getappdata.3.md
 
+if HAVE_PANDOC
 CLEANFILES += \
     $(dist_man_MANS)
+endif
 
 ### Bash Completion
 bash_completiondir = $(completionsdir)