Be more systematic about parens in C source code

Be more systematic about parens in C source code

Be more systematic about putting space before paren in calls,
and in avoiding unnecessary parentheses in macros.
This was partly inspired by my wading through gcc -E output
while debugging something else, and seeing too many parens.

This patch does not change the generated .o files on my platform.

(cherry picked from commit b6ed79b71ccb3df8df05531d473ff9510cf9a39f)