Fix whitespace in CMakeLists.txt

- all spaces no tabs
- indent with 4 spaces everywhere
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index a0fadad..585e75e 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -87,62 +87,62 @@
 )
 
 if(WIN32)
-set(libs ws2_32)
+    set(libs ws2_32)
 endif(WIN32)
 
 if(CMAKE_COMPILER_IS_GNUCC)
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wmissing-declarations -Wmissing-prototypes")
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wmissing-declarations -Wmissing-prototypes")
 endif(CMAKE_COMPILER_IS_GNUCC)
 
 if(CMAKE_COMPILER_IS_CLANG)
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wmissing-declarations -Wmissing-prototypes -Wdocumentation -Wno-documentation-deprecated-sync -Wunreachable-code")
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wmissing-declarations -Wmissing-prototypes -Wdocumentation -Wno-documentation-deprecated-sync -Wunreachable-code")
 endif(CMAKE_COMPILER_IS_CLANG)
 
 if (NOT USE_STATIC_MBEDTLS_LIBRARY AND NOT USE_SHARED_MBEDTLS_LIBRARY)
-	message(FATAL_ERROR "Need to choose static or shared mbedtls build!")
+    message(FATAL_ERROR "Need to choose static or shared mbedtls build!")
 endif(NOT USE_STATIC_MBEDTLS_LIBRARY AND NOT USE_SHARED_MBEDTLS_LIBRARY)
 
 if(USE_STATIC_MBEDTLS_LIBRARY AND USE_SHARED_MBEDTLS_LIBRARY)
-	# if we build both static an shared, then let
-	# tests and programs link to the shared lib target
-	set(mbedtls_static_target "mbedtls_static")
+    # if we build both static an shared, then let
+    # tests and programs link to the shared lib target
+    set(mbedtls_static_target "mbedtls_static")
 elseif(USE_STATIC_MBEDTLS_LIBRARY)
-	set(mbedtls_static_target "mbedtls")
+    set(mbedtls_static_target "mbedtls")
 endif()
 
 if(USE_STATIC_MBEDTLS_LIBRARY)
-	add_library(${mbedtls_static_target} STATIC ${src})
-	set_target_properties(${mbedtls_static_target} PROPERTIES OUTPUT_NAME mbedtls)
-	target_link_libraries(${mbedtls_static_target} ${libs})
+    add_library(${mbedtls_static_target} STATIC ${src})
+    set_target_properties(${mbedtls_static_target} PROPERTIES OUTPUT_NAME mbedtls)
+    target_link_libraries(${mbedtls_static_target} ${libs})
 
-	if(ZLIB_FOUND)
-		target_link_libraries(${mbedtls_static_target} ${ZLIB_LIBRARIES})
-	endif(ZLIB_FOUND)
+    if(ZLIB_FOUND)
+        target_link_libraries(${mbedtls_static_target} ${ZLIB_LIBRARIES})
+    endif(ZLIB_FOUND)
 
-	if(LINK_WITH_PTHREAD)
+    if(LINK_WITH_PTHREAD)
         target_link_libraries(${mbedtls_static_target} pthread)
-	endif()
+    endif()
 
-	install(TARGETS ${mbedtls_static_target}
-			DESTINATION ${LIB_INSTALL_DIR}
-			PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+    install(TARGETS ${mbedtls_static_target}
+        DESTINATION ${LIB_INSTALL_DIR}
+        PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
 endif()
 
 if(USE_SHARED_MBEDTLS_LIBRARY)
-	add_library(mbedtls SHARED ${src})
-	set_target_properties(mbedtls PROPERTIES VERSION 1.4.0 SOVERSION 8)
+    add_library(mbedtls SHARED ${src})
+    set_target_properties(mbedtls PROPERTIES VERSION 1.4.0 SOVERSION 8)
 
-	target_link_libraries(mbedtls ${libs})
+    target_link_libraries(mbedtls ${libs})
 
-	if(ZLIB_FOUND)
-		target_link_libraries(mbedtls ${ZLIB_LIBRARIES})
-	endif(ZLIB_FOUND)
+    if(ZLIB_FOUND)
+        target_link_libraries(mbedtls ${ZLIB_LIBRARIES})
+    endif(ZLIB_FOUND)
 
-	if(LINK_WITH_PTHREAD)
+    if(LINK_WITH_PTHREAD)
         target_link_libraries(mbedtls pthread)
-	endif()
+    endif()
 
-	install(TARGETS mbedtls
-			DESTINATION ${LIB_INSTALL_DIR}
-			PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+    install(TARGETS mbedtls
+            DESTINATION ${LIB_INSTALL_DIR}
+            PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
 endif(USE_SHARED_MBEDTLS_LIBRARY)