XL: De-duplicate shared object creation flags

The XL `-qmkshrobj` flag creates shared objects on all platforms.
Move the flag out of the per-platform modules into the per-compiler
module for XL.

Modules/Compiler/XL.cmake

@@ -18,6 +18,8 @@ macro(__compiler_xl lang)
   set(CMAKE_${lang}_RESPONSE_FILE_FLAG "-qoptfile=")
   set(CMAKE_${lang}_RESPONSE_FILE_LINK_FLAG "-qoptfile=")
 
+  set(CMAKE_SHARED_LIBRARY_CREATE_${lang}_FLAGS "-qmkshrobj")
+
   set(CMAKE_${lang}_LINKER_WRAPPER_FLAG "-Wl,")
   set(CMAKE_${lang}_LINKER_WRAPPER_FLAG_SEP ",")
 

Modules/Platform/Apple-XL-C.cmake

@@ -1,4 +1,3 @@
-set(CMAKE_SHARED_LIBRARY_CREATE_C_FLAGS "-qmkshrobj")
 set(CMAKE_SHARED_MODULE_CREATE_C_FLAGS "-bundle")
 
 # Enable shared library versioning.

Modules/Platform/Apple-XL-CXX.cmake

@@ -1,4 +1,3 @@
-set(CMAKE_SHARED_LIBRARY_CREATE_CXX_FLAGS "-qmkshrobj")
 set(CMAKE_SHARED_MODULE_CREATE_CXX_FLAGS "-bundle")
 
 # Enable shared library versioning.

Modules/Platform/Linux-XL-C.cmake

@@ -1,2 +1 @@
-set(CMAKE_SHARED_LIBRARY_CREATE_C_FLAGS "-qmkshrobj")
 set(CMAKE_SHARED_LIBRARY_LINK_C_FLAGS "-Wl,-export-dynamic")

Modules/Platform/Linux-XL-CXX.cmake

@@ -1,2 +1 @@
-set(CMAKE_SHARED_LIBRARY_CREATE_CXX_FLAGS "-qmkshrobj")
 set(CMAKE_SHARED_LIBRARY_LINK_CXX_FLAGS "-Wl,-export-dynamic")

Modules/Platform/Linux-XL-Fortran.cmake

@@ -1,2 +1 @@
-set(CMAKE_SHARED_LIBRARY_CREATE_Fortran_FLAGS "-qmkshrobj")
 set(CMAKE_SHARED_LIBRARY_LINK_Fortran_FLAGS "-Wl,-export-dynamic")