Toolchain: Enable the -rdynamic flag in the gcc driver

Although we handle it in the linker spec file, gcc will actually reject
this argument unless it's also enabled in the option file.

CMake adds this flag if the minimum required version is 3.3 or less (see
CMP0065), so old projects would fail to compile because of this
unrecognized option.

Toolchain/Patches/gcc.patch

@@ -224,10 +224,10 @@ index 000000000..dc2f5361e
 +  } while(0);
 diff --git a/gcc/config/serenity.opt b/gcc/config/serenity.opt
 new file mode 100644
-index 000000000..6ce2af2d7
+index 000000000..2756a5575
 --- /dev/null
 +++ b/gcc/config/serenity.opt
-@@ -0,0 +1,32 @@
+@@ -0,0 +1,35 @@
 +; SerenityOS options.
 +
 +; Copyright (C) 2021 Gunnar Beutner <gunnar@beutner.name>
@@ -259,6 +259,9 @@ index 000000000..6ce2af2d7
 +pthread
 +Driver
 +
++rdynamic
++Driver
++
 +; This comment is to ensure we retain the blank line above.
 diff --git a/gcc/configure b/gcc/configure
 index 9b28369e3..6821ed4ba 100755