fixup! Convert flashrom to git

 - exploit Make's -include statement to simplify execution flow
 - expand and refine respective comment to better describe and
   match the new behavior

Change-Id: I0c66f2508cc754cf9219211a06d6f305a32c422d
Signed-off-by: Stefan Tauner <stefan.tauner@gmx.at>
Reviewed-on: https://review.coreboot.org/21830
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/Makefile b/Makefile
index d014580..1893bb1 100644
--- a/Makefile
+++ b/Makefile
@@ -526,15 +526,12 @@
 
 CLI_OBJS = cli_classic.o cli_output.o cli_common.o print.o
 
-# versioninfo.inc is used when packaging flashrom and is generated by the
-# export rule. If versioninfo.inc is not found, version info will be obtained
-# using util/getrevision.sh.
-ifeq ($(wildcard versioninfo.inc),)
+# versioninfo.inc stores metadata required to build a packaged flashrom. It is generated by the export rule and
+# imported below. If versioninfo.inc is not found and the variables are not defined by the user, the info will
+# be obtained using util/getrevision.sh, which is the common case during development.
+-include versioninfo.inc
 VERSION ?= $(shell ./util/getrevision.sh --revision)
 MAN_DATE ?= $(shell ./util/getrevision.sh --date $(PROGRAM).8.tmpl 2>/dev/null)
-else
-include versioninfo.inc
-endif
 
 # VERSION equals "offline" if online access is required but the respective git
 # config variable is not set yet.