Fix races in the Makefile of plugins/sudoers when compiled in parallel. #487
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in order to prevent the command from continuing to execute when one of the commands fails.
When one command generates multiple outputs, using a naive one-to-two depency would introduce race condition when doing parallel compilation. For example, when the rules are written in this pattern: foo.c foo.h: foo.y command foo.y generating foo.c and foo.h some-target: foo.c some command reading foo.c some-other-target: foo.h some command reading foo.h and the targets are built in parallel, `command foo.y` may be executed twice because make thinks `command foo.y` can be used to generate foo.c and can also be used to generate foo.h. What's worse, one of the commands reading foo.c or foo.h may read an incomplete input during the command generating the other one is running. This pattern happens on the rules of def_data.in and gram.y. This commit fixes this by using a stamp file to witness the execution of the `command foo.y`, following the advice in the automake manual [1]. [1]: https://www.gnu.org/software/automake/manual/html_node/Multiple-Outputs.html
The targets for generating getdate.c and gram.c/h run yacc in the same directory and post-process the generated y.tab.c/h by yacc into the final target. They both generate temporary y.tab.c/h files with the same name and they may overwrite each other if built in parallel. This commit fixes this by let yacc run in individual temporary directories to prevent them from overwriting each other.
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