Remove unused LLVMLandingPadClauseTy from Core.h (#124472)

enum LLVMLandingPadClauseTy has never been used and exists by mistake.

[This](llvm-mirror/llvm@772fe17#diff-9e2da57026497163c9f7396a48567626a0b94828a5757436ef20a4e67522525d) commit added a LLVMAddClause function that took it as a parameter. 

[Here](llvm-mirror/llvm@10c6d12#diff-6e588c82c378e251a7d265b08973d4a7312a592756f88023cd317f109083de10) the enum was removed.

And [here](llvm-mirror/llvm@e6e8826#diff-9e2da57026497163c9f7396a48567626a0b94828a5757436ef20a4e67522525d) it is added again by mistake, although the LLVMAddClause function no longer accepts it

Author: vova7878

llvm/include/llvm-c/Core.h

@@ -321,11 +321,6 @@ typedef enum {
   LLVMRealPredicateTrue   /**< Always true (always folded) */
 } LLVMRealPredicate;
 
-typedef enum {
-  LLVMLandingPadCatch,    /**< A catch clause   */
-  LLVMLandingPadFilter    /**< A filter clause  */
-} LLVMLandingPadClauseTy;
-
 typedef enum {
   LLVMNotThreadLocal = 0,
   LLVMGeneralDynamicTLSModel,