[fxbug.dev] Migrate bug numbers

This changes fxbug.dev/ URLs from Monorail bug numbers to the new
Fuchsia Issue Tracker numbers.

The migration to the new issue tracker was announced here:
https://groups.google.com/a/fuchsia.dev/g/announce/c/GOYfJozEqmk/m/qsGsaJ7UAAAJ

Bug: 298074672
Change-Id: I149336f27f2f63f344eed53f42459582c03fbf53
diff --git a/src/base/utils_unittest.cc b/src/base/utils_unittest.cc
index 45265de..9a39b0d 100644
--- a/src/base/utils_unittest.cc
+++ b/src/base/utils_unittest.cc
@@ -142,7 +142,7 @@
 }
 
 // Fuchsia doesn't currently support sigaction(), see
-// https://fxbug.dev/30518 .
+// https://fxbug.dev/42105390 .
 #if PERFETTO_BUILDFLAG(PERFETTO_OS_LINUX) ||   \
     PERFETTO_BUILDFLAG(PERFETTO_OS_ANDROID) || \
     PERFETTO_BUILDFLAG(PERFETTO_OS_APPLE)