Fix data race on cfiExportsMap

cfiExportsMap was reinitialized for every module, which caused
data races.  Create the path from the string on each use
instead.

Bug: 77234104
Test: m nothing with race detector turned on
Change-Id: Ibca3149dcbe8a9d4d9f7ec6dd0b164697e7ae5cd
Merged-In: Ibca3149dcbe8a9d4d9f7ec6dd0b164697e7ae5cd
(cherry picked from commit 1218a19f)