add static_stdlib option as there is no static gcc library on rockylinux (#248)

### What problem were solved in this pull request?

Issue Number: close #247 

Problem:
Compile miniob with static gcc and g++ failed while there is no static
gcc library on rockylinux.

### What is changed and how it works?
Add cmake option static_stdlib with default value off.
In normal case, we compile miniob and run/debug it on the same machine,
so dynamic linking works fun. If we want to move observer binary to
other machine and test, we can recompile miniob with static_stdlib ON.

CMakeLists.txt

@@ -13,6 +13,7 @@ SET(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${CMAKE_SOURCE_DIR}/cmake)
 OPTION(ENABLE_ASAN "Enable build with address sanitizer" ON)
 OPTION(WITH_UNIT_TESTS "Compile miniob with unit tests" ON)
 OPTION(CONCURRENCY "Support concurrency operations" OFF)
+OPTION(STATIC_STDLIB "Link std library static or dynamic, such as libgcc, libstdc++, libasan" OFF)
 
 MESSAGE(STATUS "HOME dir: $ENV{HOME}")
 #SET(ENV{变量名} 值)
@@ -55,13 +56,13 @@ IF (CONCURRENCY)
 ENDIF (CONCURRENCY)
 
 MESSAGE(STATUS "CMAKE_CXX_COMPILER_ID is " ${CMAKE_CXX_COMPILER_ID})
-IF ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
+IF ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" AND ${STATIC_STDLIB})
     ADD_LINK_OPTIONS(-static-libgcc -static-libstdc++)
 ENDIF()
 
 IF (ENABLE_ASAN)
     SET(CMAKE_COMMON_FLAGS "${CMAKE_COMMON_FLAGS} -fno-omit-frame-pointer -fsanitize=address")
-    IF ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
+    IF ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" AND ${STATIC_STDLIB})
         ADD_LINK_OPTIONS(-static-libasan)
     ENDIF()
 ENDIF()