Makefile: specify version.h as a dependency of all object files

[trofi]

Otherwise parallel builds fail occasionally as:

$ make --shuffle -j
...
g++ -c   -O3 -D__STDC_FORMAT_MACROS   argStruct.cpp
g++ -c   -O3 -D__STDC_FORMAT_MACROS   ancestral_likes.cpp
gcc -c   -O3 -D__STDC_FORMAT_MACROS   fet.c
g++ -c   -O3 -D__STDC_FORMAT_MACROS   abcGL.cpp
g++ -c   -O3 -D__STDC_FORMAT_MACROS   pop1_read.cpp
g++ -c   -O3 -D__STDC_FORMAT_MACROS   angsd.cpp
g++ -c   -O3 -D__STDC_FORMAT_MACROS   abcHWE_F.cpp
gcc -c   -O3 -D__STDC_FORMAT_MACROS   kprobaln.c
g++ -c   -O3 -D__STDC_FORMAT_MACROS   mpileup.cpp
argStruct.cpp:3:10: fatal error: version.h: No such file or directory
    3 | #include "version.h"
      |          ^~~~~~~~~~~
compilation terminated.
angsd.cpp:11:10: fatal error: version.h: No such file or directory
   11 | #include "version.h"
      |          ^~~~~~~~~~~

Before the change it was enough to try to build angsd with 1-2 make --shuffle runs to get the failure. After the change the build survives 20 rebuilds.

[ANGSD]

Hi @trofi, thanks for this input. I had not heard about the --shuffle. There were multiple problems in my Makefiles that the --shuffle parameter helped me find.

I made a different fix by using the. .WAIT in the makefile rather than including the version. h in all objects as proposed in this PR. I will let the PR be open for now in case my fix caused other problems.

[trofi]

I think there are a few problems with .WAIT solution:

1. (minor) it was added in recently released GNU make 4.4, thus might not be widely supported
2. (major) it does not add direct dependency between version.h and object files derived from source files that use it. Those are currently: angsd.cpp. argStruct.cpp and multiReader.cpp.

[2.] means that more directed builds like $ make angsd.o will still fail to build even in presence of .WAIT. To fix it sometimes build systems manually or automatically generate dependencies like:

angsd.o: version.h
argStruct.o: version.h
multiReader.o: version.h