Build: Add stub functions of system calls

GNU Arm compiler version greater equal than *11.3.Rel1*
has a linker issue that required system calls are missing,
such as _read and _write. Add stub functions of required
system calls to solve this issue.

Signed-off-by: Chendi Sun <chendi.sun@arm.com>
Change-Id: I1384a405174097639e4c7bb71f19d01a66318a2d
diff --git a/toolchain_GNUARM.cmake b/toolchain_GNUARM.cmake
index 1c4d3c7..d905e30 100644
--- a/toolchain_GNUARM.cmake
+++ b/toolchain_GNUARM.cmake
@@ -170,9 +170,12 @@
                             " See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99157 for the issue detail.")
     endif()
 
+    # GNU Arm compiler version greater equal than *11.3.Rel1*
+    # has a linker issue that required system calls are missing,
+    # such as _read and _write. Add stub functions of required
+    # system calls to solve this issue.
     if (GCC_VERSION VERSION_GREATER_EQUAL 11.3.1)
-        message(FATAL_ERROR "GNU Arm compiler version greater and equal than *11.3.Rel1* has a linker issue in syscall."
-                            " Select other GNU Arm compiler versions instead.")
+        set(CONFIG_GNU_SYSCALL_STUB_ENABLED TRUE)
     endif()
 
     unset(CMAKE_C_FLAGS_INIT)