[Getdp] make install failure ("GMSH_LIB" -> "GETDP_LIB")

[Sebastian Schöps]

Dear all, 

when compiling getdp on my Mac with ENABLE_BUILD_SHARED=ON cmake tries to install the resulting dylib in /usr/local/lib/libGmsh.dylib instead of /usr/local/lib/. Probably "DESTINATION ${GMSH_LIB}" -> "DESTINATION ${GETDP_LIB}" (e.g. CMakeLists.txt:772)?

Discussion started when creating a formula for brew: https://github.com/Homebrew/homebrew-science/commit/cadb6c05268ffd67ee5a4db9d172003b27df1ade

Kind regards from Darmstadt, 
Sebastian