1. WB_IsJVMTIIncluded function uses runtime check. Most likely compiler elides the check, but for consistency it would be better to implements the function the same way as others:

WB_ENTRY(jboolean, WB_IsJVMTIIncluded(JNIEnv* env, jobject wb))
  #if INCLUDE_JVMTI
     return JNI_TRUE;
  #else
     return JNI_FALSE;
  #endif
WB_END

2. function names are inconsistent:

isCDSIncludedInVmBuild / WB_IsCDSIncludedInVmBuild
isJFRIncludedInVmBuild / WB_IsJFRIncludedInVmBuild
isC2OrJVMCIIncludedInVmBuild / WB_isC2OrJVMCIIncludedInVmBuild
isJVMTIIncluded / WB_IsJVMTIIncluded

As per David suggestion the functions don't need to have "InVmBuild" in the name as it's redundant/unnecessary