${pc_top_builddir} expands to \$\(top_builddir\), which is pretty clearly intended to be a make variable reference, except the shell escaping breaks it.
Fixed in: commit 1b1bd80f5fff35f20903489b0e988ba7a1159f95 Author: Tollef Fog Heen <tfheen@err.no> Date: Wed Apr 13 22:02:51 2011 +0200 Allow $() through unescaped. $(foo) is used for make escapes, so allow them through. Freedesktop #33920
*** Bug 28453 has been marked as a duplicate of this bug. ***
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