Makefile: clarify definition of TEST_OBJS

The definition of TEST_OBJS in commit daa99a91 (Makefile: make sure test helpers are rebuilt when headers change, 2010-01-26) moved a use of $X to before the platform-specific section where it gets defined. There are at least two ways to fix that: - Change the definition of TEST_OBJS to use the = delayed evaluation operator. This way, one need not worry about $(X) needing to be defined before TEST_OBJS is set. - Move the definition of TEST_OBJS to below the definition of $X. Carry out the second. The later site of definition makes the code more readable, since now a reader only has to look down one line to see what TEST_OBJS is meant to be used for. Oddly enough, with or without this change the behavior of the Makefile is the same. Since TEST_PROGRAMS is defined with delayed evaluation, the value of TEST_OBJS := $(patsubst test-%$X,test-%.o,$(TEST_PROGRAMS)) is independent of the value of $X when it is evaluated: the $X in the pattern and the $X in $(TEST_PROGRAMS) will simply always cancel out. Make sure $X has the expected expansion anyway to make the code and the reader’s sanity more robust in the face of future changes. Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>