getentropy: Add Git hashes corresponding to SVN references

getentropy has a comment about a special case to support kernels between
SVN revisions r331280 and r337999.  Add the corresponding Git hashes so
there's a usable reference after Subversion infrastructure disappears.

Sponsored by:	The FreeBSD Foundation

lib/libc/gen/getentropy.c

@@ -125,11 +125,11 @@ __ssp_real(getentropy)(void *buf, size_t buflen)
 				switch (errno) {
 				case ECAPMODE:
 					/*
-					 * Kernel >= r331280 and < r337999
-					 * will return ECAPMODE when the
-					 * caller is already in capability
-					 * mode, fallback to traditional
-					 * method in this case.
+					 * Kernel >= r331280 (4948f7bf1153)
+					 * and < r337999 (ed1fa01ac45a) will
+					 * return ECAPMODE when the caller is
+					 * already in capability mode; fallback
+					 * to traditional method in this case.
 					 */
 					have_getrandom = false;
 					continue;