PostGIS has the following requirements for building and usage:
A complete configured and built PostgreSQL source code tree. PostGIS uses definitions from the PostgreSQL configure/build process to conform to the particular platform you are building on. PostgreSQL is available from http://www.postgresql.org.
GNU C compiler (gcc). Some other ANSI C compilers can be used to compile PostGIS, but we find far fewer problems when compiling with gcc.
GNU Make (gmake or make). For many systems, GNU make is the default version of make. Check the version by invoking make -v. Other versions of make may not process the PostGIS Makefile properly.
(Optional) Proj4 reprojection library. The Proj4 library is used to provide coordinate reprojection support within PostGIS. Proj4 is available for download from http://www.remotesensing.org/proj.