At the time of this writing, it seems that CMake only uses "-rdynamic"
on Linux:

```
$ git clone https://github.com/Kitware/CMake.git
Cloning into 'CMake'...
remote: Enumerating objects: 335, done.
remote: Counting objects: 100% (335/335), done.
remote: Compressing objects: 100% (254/254), done.
remote: Total 272793 (delta 86), reused 125 (delta 79), pack-reused 272458
Receiving objects: 100% (272793/272793), 88.11 MiB | 29.21 MiB/s, done.
Resolving deltas: 100% (207174/207174), done.
$ cd CMake/Modules/
Modules$ fgrep -r -w rdynamic .
./Platform/Linux-TinyCC-C.cmake:set(CMAKE_EXE_EXPORTS_C_FLAG "-rdynamic ")
./Platform/Linux-NAG-Fortran.cmake:set(CMAKE_SHARED_LIBRARY_LINK_Fortran_FLAGS "-Wl,-rdynamic")
./Platform/Linux-Intel.cmake:  set(CMAKE_SHARED_LIBRARY_LINK_${lang}_FLAGS "-rdynamic")
./Platform/Linux-GNU.cmake:  set(CMAKE_SHARED_LIBRARY_LINK_${lang}_FLAGS "-rdynamic")
```

So the conditional has been modified accordingly.

Fix typo by changing "STATIC" to "CMARK_STATIC".

LINUX is not a CMake platform variable, so the expression has been
updated accordingly and the build functionality verified.