The omission was discovered while cross-compiling LilyPond with mingw
11.0.1: without this addition, linking with libguile causes the error
undefined reference to `BCryptGenRandom'
* meta/Makefile.am (dependency_substitutions): Add ‘LIB_GETRANDOM’.
* meta/guile-3.0-uninstalled.pc.in (Libs.private): Likewise.
* meta/guile-3.0.pc.in (Libs.private): Likewise.
* NEWS: Update.
Signed-off-by: Ludovic Courtès <ludo@gnu.org>