Do not abuse $(EXTRA_PROGRAMS).

We don't want to compile some programs on Windows. There was already a
Makefile variable EXTRA_PROGRAMS, which we used to achieve this. But
this is not exactly self-explanatory. So we name the variable
POSIX_ONLY_PROGRAMS and reinstate the old EXTRA_PROGRAMS.

Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>

Makefile

@@ -268,6 +268,7 @@ PROGRAMS = \
 	git-upload-pack$X \
 	git-pack-redundant$X git-var$X \
 	git-merge-tree$X \
+	$(POSIX_ONLY_PROGRAMS) \
 	$(EXTRA_PROGRAMS)
 
 # Empty...
@@ -551,7 +552,7 @@ ifneq (,$(findstring MINGW,$(uname_S)))
 	NO_MKDTEMP = YesPlease
 	NO_SVN_TESTS = YesPlease
 	NO_PERL_MAKEMAKER = YesPlease
-	NO_EXTRA_PROGRAMS = YesPlease
+	NO_POSIX_ONLY_PROGRAMS = YesPlease
 	COMPAT_CFLAGS += -D__USE_MINGW_ACCESS -DNOGDI -Icompat
 	COMPAT_CFLAGS += -DSTRIP_EXTENSION=\".exe\"
 	COMPAT_OBJS += compat/mingw.o compat/fnmatch.o compat/regex.o
@@ -621,8 +622,8 @@ ifdef ZLIB_PATH
 endif
 EXTLIBS += -lz
 
-ifndef NO_EXTRA_PROGRAMS
-	EXTRA_PROGRAMS += \
+ifndef NO_POSIX_ONLY_PROGRAMS
+	POSIX_ONLY_PROGRAMS = \
 		git-daemon$X \
 		git-imap-send$X
 endif