当我尝试使用ree-1.8.7-2011.03在Ubuntu上安装mysql2时，我得到：
# gem install mysql2
Building native extensions. This could take a while...
错误：安装mysql2时出错： 错误：无法构建gem原生扩展。
/usr/local/rvm/rubies/ree-1.8.7-2011.03/bin/ruby extconf.rb
checking for rb_thread_blocking_region()... no
checking for rb_wait_for_single_fd()... no
checking for mysql.h... yes
checking for errmsg.h... yes
checking for mysqld_error.h... yes
creating Makefile
make
gcc -I. -I/opt/local/include -I. -I/usr/local/rvm/rubies/ree-1.8.7-
2011.03/lib/ruby/1.8/i686-linux -I. -DHAVE_MYSQL_H -DHAVE_ERRMSG_H -DHAVE_MYSQLD_ERROR_H -D_FILE_OFFSET_BITS=64 -I/usr/include -fPIC -g -static-libgcc -fno-omit-frame-pointer -fPIC -g -static-libgcc -fno-omit-frame-pointer -fno-strict-aliasing -DMY_PTHREAD_FASTMUTEX=1 -fPIC -g -O2 -Wall -funroll-loops -c client.c
gcc -I. -I/opt/local/include -I. -I/usr/local/rvm/rubies/ree-1.8.7-2011.03/lib/ruby/1.8/i686-linux -I. -DHAVE_MYSQL_H -DHAVE_ERRMSG_H -DHAVE_MYSQLD_ERROR_H -D_FILE_OFFSET_BITS=64 -I/usr/include -fPIC -g -static-libgcc -fno-omit-frame-pointer -fPIC -g -static-libgcc -fno-omit-frame-pointer -fno-strict-aliasing -DMY_PTHREAD_FASTMUTEX=1 -fPIC -g -O2 -Wall -funroll-loops -c mysql2_ext.c
./client.h:16: warning: ‘rb_thread_blocking_region’ defined but not used
gcc -I. -I/opt/local/include -I. -I/usr/local/rvm/rubies/ree-1.8.7-2011.03/lib/ruby/1.8/i686-linux -I. -DHAVE_MYSQL_H -DHAVE_ERRMSG_H -DHAVE_MYSQLD_ERROR_H -D_FILE_OFFSET_BITS=64 -I/usr/include -fPIC -g -static-libgcc -fno-omit-frame-pointer -fPIC -g -static-libgcc -fno-omit-frame-pointer -fno-strict-aliasing -DMY_PTHREAD_FASTMUTEX=1 -fPIC -g -O2 -Wall -funroll-loops -c result.c
gcc -shared -o mysql2.so client.o mysql2_ext.o result.o -L. -L/usr/local/rvm/rubies/ree-1.8.7-2011.03/lib -Wl,-R/usr/local/rvm/rubies/ree-1.8.7-2011.03/lib -L. -rdynamic -Wl,- export-dynamic -Wl,-rpath,/usr/lib -L/usr/lib -lmysqlclient_r -lpthread -lm -lrt -ldl -L/opt/local/lib -lrt -ldl -lcrypt -lm -lc
/usr/bin/ld: cannot find -lmysqlclient_r
collect2: ld returned 1 exit status
make: *** [mysql2.so] Error 1
我不确定错误是什么。对原因有任何想法吗？