math/gfan: pass maintainership

o Update URL in MASTER_SITES to current address
o Update MAINTAINER
o Remove post-patch target as it is not needed

• Use LDFLAGS instead of the non-standard variable

	  ADDITIONALLINKOPTIONS.

• Replace "${REINPLACE_CMD} 's,log2,gfan_log2,g'" by appropriate

	  patch files as the command triggers multiple warnings. log2 is
	  a macro defined in src/log.h. The name of this macro is in
	  conflict with the function log2 from math.h. To avoid errors
	  when compiling the code, the above renaming is necessary.
	  Furthermore, PHB 4.4.3 strongly suggests using patch files
	  instead of REINPLACE_CMD for static content.

o Sort pkg-plist alphabetically as required by PHB 3.2.2
o Shorten pkg-descr and make it less technical

PR: 250879
Submitted by: Moritz Schmitt (maintainer)