[mlir][CAPI] Add the missing <stdbool.h> in Support.h

This was likely an oversight in https://reviews.llvm.org/D92292

Reviewed By: stellaraccident

Differential Revision: https://reviews.llvm.org/D93588

Author: Gnimuc

mlir/include/mlir-c/Support.h

@@ -15,6 +15,7 @@
 #ifndef MLIR_C_SUPPORT_H
 #define MLIR_C_SUPPORT_H
 
+#include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>