tests: extend test coverage of getuid/getgid family syscalls

Add strict tests for getuid, getuid32, getgid, getgid32, geteuid,
geteuid32, getegid, and getegid32 syscalls.

* tests/getegid.c: New file.
* tests/getegid.test: New test.
* tests/getegid32.c: New file.
* tests/getegid32.test: New test.
* tests/geteuid.c: New file.
* tests/geteuid.test: New test.
* tests/geteuid32.c: New file.
* tests/geteuid32.test: New test.
* tests/getgid.c: New file.
* tests/getgid.test: New test.
* tests/getgid32.c: New file.
* tests/getgid32.test: New test.
* tests/getuid.c: New file.
* tests/getuid.test: New test.
* tests/getuid32.c: New file.
* tests/getuid32.test: New test.
* tests/.gitignore: Add getuid, getuid32, getgid, getgid32, geteuid,
* geteuid32, getegid, and getegid32.
* tests/Makefile.am (check_PROGRAMS): Likewise.
(DECODER_TESTS): Add getegid.test, getegid32.test, geteuid.test,
geteuid32.test, getgid.test, getgid32.test, getuid.test,
and getuid32.test.
diff --git a/tests/.gitignore b/tests/.gitignore
index f4bbe29..e8cbdf7 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -59,6 +59,12 @@
 getcwd
 getdents
 getdents64
+getegid
+getegid32
+geteuid
+geteuid32
+getgid
+getgid32
 getgroups
 getgroups32
 getrandom
@@ -67,6 +73,8 @@
 getresuid
 getresuid32
 getrusage
+getuid
+getuid32
 getxxid
 inet-cmsg
 ioctl