Don't build C examples if we're not building wrappers.

examples/CMakeLists.txt

@@ -50,9 +50,9 @@ FOREACH(EX_ROOT ${CPP_EXAMPLES})
 
 ENDFOREACH(EX_ROOT ${CPP_EXAMPLES})
 
-INCLUDE_DIRECTORIES(BEFORE ${PROJECT_BINARY_DIR}/wrappers)
-
-FOREACH(EX_ROOT ${C_EXAMPLES})
+IF(OPENMM_BUILD_API_WRAPPERS)
+  INCLUDE_DIRECTORIES(BEFORE ${PROJECT_BINARY_DIR}/wrappers)
+  FOREACH(EX_ROOT ${C_EXAMPLES})
     IF (BUILD_TESTING_SHARED)
         # Link with shared library
 		# We need at least one .cpp here to get CMake to include
@@ -81,7 +81,8 @@ FOREACH(EX_ROOT ${C_EXAMPLES})
 
     INSTALL(FILES ${EX_ROOT}.c DESTINATION examples)
 
-ENDFOREACH(EX_ROOT ${C_EXAMPLES})
+  ENDFOREACH(EX_ROOT ${C_EXAMPLES})
+ENDIF(OPENMM_BUILD_API_WRAPPERS)
 
 FOREACH(EX_ROOT ${F_EXAMPLES})
     INSTALL(FILES ${EX_ROOT}.f90 DESTINATION examples)