mpfr 3.1.0 安装gcc必需文件

安装GCC必需的三个文件（gmp、mpfr、mpc）之一，mpfr，安装此库之前需要先安装M4，否则无法完成安装。另：上述文件我已上传至我的资源，如有需要下载即可。 压缩包中有多种格式，择一安装即可。 The MPFR library is a C library for multiple-precision floating-point computations with correct rounding. MPFR has continuously been supported by the INRIA and the current main authors come from the Caramel and Arénaire project-teams at Loria (Nancy, France) and LIP (Lyon, France) respectively; see more on the credit page. MPFR is based on the GMP multiple-precision library.