build: fix race between 'clean' and generated files

When a parallel build is invoked using "make -j4" there is a race
between EXTRA_DEPS ('clean') and generating files:

  CPU1                             CPU2
  ----                             ----
  create cli/generated-config.go
                                   rm cli/generated-config.go
  go build -> error: generated-config.go doesn't exist!

Previous commits ensured that targets relying on version information
like VERSION and COMMIT declare appropriate dependencies.  Therefore
make is now able to detect changes and rebuild targets as needed.  It is
no longer necessary to abuse the clean target to force a rebuild.

Fixes: #1540
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Makefile

@@ -69,8 +69,6 @@ BINLIBEXECLIST += $(NETMON_TARGET)
 
 DESTDIR := /
 
-installing = $(findstring install,$(MAKECMDGOALS))
-
 ifeq ($(PREFIX),)
 PREFIX        := /usr
 EXEC_PREFIX   := $(PREFIX)/local
@@ -85,12 +83,6 @@ FCBINDIR      := $(PREFIXDEPS)/bin
 SYSCONFDIR    := /etc
 LOCALSTATEDIR := /var
 
-ifeq (,$(installing))
-    # Force a rebuild to ensure version details are correct
-    # (but only for a non-install build phase).
-    EXTRA_DEPS = clean
-endif
-
 LIBEXECDIR := $(PREFIXDEPS)/libexec
 SHAREDIR := $(PREFIX)/share
 DEFAULTSDIR := $(SHAREDIR)/defaults
@@ -400,7 +392,7 @@ endef
 
 GENERATED_FILES += $(CLI_DIR)/config-generated.go
 
-$(TARGET_OUTPUT): $(EXTRA_DEPS) $(SOURCES) $(GENERATED_FILES) $(MAKEFILE_LIST) | show-summary
+$(TARGET_OUTPUT): $(SOURCES) $(GENERATED_FILES) $(MAKEFILE_LIST) | show-summary
 	$(QUIET_BUILD)(cd $(CLI_DIR) && go build $(BUILDFLAGS) -o $@ .)
 
 $(SHIMV2_OUTPUT):