Build with the system NSPR library instead of the bundled version.

Originally based on this Debian patch:
https://salsa.debian.org/chromium-team/chromium/-/blob/master/debian/patches/system/nspr.patch

diff --git a/base/BUILD.gn b/base/BUILD.gn
--- a/base/BUILD.gn
+++ b/base/BUILD.gn
@@ -184,6 +184,12 @@ buildflag_header("ios_cronet_buildflags") {
   flags = [ "CRONET_BUILD=$is_cronet_build" ]
 }
 
+if (is_linux) {
+  ldflags = [
+    "-lnspr4",
+  ]
+}
+
 # Base and everything it depends on should be a static library rather than
 # a source set. Base is more of a "library" in the classic sense in that many
 # small parts of it are used in many different contexts. This combined with a
@@ -838,8 +844,6 @@ mixed_component("base") {
     "third_party/cityhash_v103/src/city_v103.cc",
     "third_party/cityhash_v103/src/city_v103.h",
     "third_party/icu/icu_utf.h",
-    "third_party/nspr/prtime.cc",
-    "third_party/nspr/prtime.h",
     "third_party/superfasthash/superfasthash.c",
     "thread_annotations.h",
     "threading/hang_watcher.cc",
diff --git a/base/time/pr_time_unittest.cc b/base/time/pr_time_unittest.cc
--- a/base/time/pr_time_unittest.cc
+++ b/base/time/pr_time_unittest.cc
@@ -6,7 +6,7 @@
 #include <time.h>
 
 #include "base/compiler_specific.h"
-#include "base/third_party/nspr/prtime.h"
+#include <nspr/prtime.h>
 #include "base/time/time.h"
 #include "build/build_config.h"
 #include "testing/gtest/include/gtest/gtest.h"
diff --git a/base/time/time.cc b/base/time/time.cc
--- a/base/time/time.cc
+++ b/base/time/time.cc
@@ -21,7 +21,7 @@
 #include <utility>
 
 #include "base/strings/stringprintf.h"
-#include "base/third_party/nspr/prtime.h"
+#include <nspr/prtime.h>
 #include "base/time/time_override.h"
 #include "build/build_config.h"
 #include "third_party/abseil-cpp/absl/types/optional.h"
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<div class='path'>path: <a href='/guix/log/?id=44636fd92d69749f1d16f11d9bfd7cf7ea616812'>root</a>/<a href='/guix/log/gnu?id=44636fd92d69749f1d16f11d9bfd7cf7ea616812'>gnu</a>/<a href='/guix/log/gnu/packages?id=44636fd92d69749f1d16f11d9bfd7cf7ea616812'>packages</a>/<a href='/guix/log/gnu/packages/monitoring.scm?id=44636fd92d69749f1d16f11d9bfd7cf7ea616812'>monitoring.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/monitoring.scm?id=44636fd92d69749f1d16f11d9bfd7cf7ea616812&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-06-25 23:46:03 +0200'>2023-06-25</span></td><td><a href='/guix/commit/gnu/packages/monitoring.scm?id=81cad577099d7fd3972daadefd619eca48fe6e98'>gnu: fswatch: Update to 1.17.1.</a></td><td>Greg Hogan</td></tr>
<tr><td><span title='2023-06-20 22:13:46 +0100'>2023-06-20</span></td><td><a href='/guix/commit/gnu/packages/monitoring.scm?id=9d3ce0c408a66433f0ce56ec2ca9dddf966e626d'>gnu: batsignal: Update to 1.6.4.</a></td><td>kiasoc5</td></tr>
<tr><td><span title='2023-04-24 12:17:17 +0200'>2023-04-24</span></td><td><a href='/guix/commit/gnu/packages/monitoring.scm?id=f4a6a65d683762bd58944c7d555dc79708e5981e'>gnu: fatrace: Update to 0.17.0.</a></td><td>Raphaël Mélotte</td></tr>
<tr><td><span title='2023-03-20 23:10:15 -0400'>2023-03-20</span></td><td><a href='/guix/commit/gnu/packages/monitoring.scm?id=b4fb941957ea68a5e708525a8bebeacdc3d70959'>gnu: zabbix-agentd: Update to 6.0.14.</a></td><td>Kaelyn Takata</td></tr>
<tr><td><span title='2023-02-19 01:00:01 +0100'>2023-02-19</span></td><td><a href='/guix/commit/gnu/packages/monitoring.scm?id=1e6ddceb8318d413745ca1c9d91fde01b1e0364b'>gnu: Use HTTPS package home pages wherever possible.</a></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2023-02-16 22:41:03 +0200'>2023-02-16</span></td><td><a href='/guix/commit/gnu/packages/monitoring.scm?id=672036c6dfe508810b565f4cf38e4f2aad2f7151'>gnu: Remove unneeded module imports.</a></td><td>Efraim Flashner</td></tr>