Reapply "libprocessgroup: Remove __BEGIN_DECLS and __END_DECLS"

This reverts commit fdaaef95238d1de873040482938585cb01f724d6.

Reason for revert: should be safe to reapply post
  https://android-review.git.corp.google.com/c/platform/packages/modules/Connectivity/+/3369257

Test: TreeHugger
Bug: 379796721
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I1a24791713484461345312a34777c2266e443cee
diff --git a/libprocessgroup/include/processgroup/processgroup.h b/libprocessgroup/include/processgroup/processgroup.h
index d27b568..6a026a7 100644
--- a/libprocessgroup/include/processgroup/processgroup.h
+++ b/libprocessgroup/include/processgroup/processgroup.h
@@ -16,7 +16,6 @@
 
 #pragma once
 
-#include <sys/cdefs.h>
 #include <sys/types.h>
 #include <initializer_list>
 #include <span>
@@ -24,8 +23,6 @@
 #include <string_view>
 #include <vector>
 
-__BEGIN_DECLS
-
 static constexpr std::string CGROUPV2_HIERARCHY_NAME = "cgroup2";
 
 bool CgroupsAvailable();
@@ -39,8 +36,6 @@
 bool SetProcessProfiles(uid_t uid, pid_t pid, const std::vector<std::string>& profiles);
 bool SetUserProfiles(uid_t uid, const std::vector<std::string>& profiles);
 
-__END_DECLS
-
 bool SetTaskProfiles(pid_t tid, std::initializer_list<std::string_view> profiles,
                      bool use_fd_cache = false);
 bool SetProcessProfiles(uid_t uid, pid_t pid, std::initializer_list<std::string_view> profiles);
@@ -50,7 +45,6 @@
 bool SetProcessProfiles(uid_t uid, pid_t pid, std::span<const std::string_view> profiles);
 #endif
 
-__BEGIN_DECLS
 
 #ifndef __ANDROID_VNDK__
 
@@ -96,5 +90,3 @@
 bool isProfileValidForProcess(const std::string& profile_name, uid_t uid, pid_t pid);
 
 #endif // __ANDROID_VNDK__
-
-__END_DECLS