Clean build system

Don't require environmnet variables SIMPATH and FAIRROOTPATH when building
flesnet and NicaFemto. Pass the corresponding CMake variables to the build
processes of the packages.

external/InstallFlesnet.cmake

@@ -34,10 +34,13 @@ endif()
 ExternalProject_Add(
   flesnet
   SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/flesnet
-  CMAKE_CACHE_ARGS
-  -DINCLUDE_ZMQ:BOOL=TRUE
-  -DCMAKE_POSITION_INDEPENDENT_CODE:BOOL=ON
-  -DOPENSSL_ROOT_DIR:FILEPATH=${OPENSSL_PATH}
+  CONFIGURE_COMMAND ${CMAKE_COMMAND} -E env SIMPATH=${SIMPATH}
+             ${CMAKE_COMMAND}
+             -G ${CMAKE_GENERATOR}
+             -DINCLUDE_ZMQ:BOOL=TRUE
+             -DCMAKE_POSITION_INDEPENDENT_CODE:BOOL=ON
+             -DOPENSSL_ROOT_DIR:FILEPATH=${OPENSSL_PATH}
+             ${CMAKE_CURRENT_SOURCE_DIR}/flesnet
   BUILD_IN_SOURCE 0
   LOG_DOWNLOAD 1 LOG_CONFIGURE 1 LOG_BUILD 1 LOG_INSTALL 1
   BUILD_COMMAND ${CMAKE_COMMAND} --build . -j 1 --target logging fles_ipc

external/InstallNicaFemto.cmake

@@ -32,7 +32,9 @@ ExternalProject_Add(NICAFEMTO
   SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/NicaFemto
   BUILD_BYPRODUCTS ${NICAFEMTO_LIBRARY}
   LOG_DOWNLOAD 1 LOG_CONFIGURE 1 LOG_BUILD 1 LOG_INSTALL 1
-  CMAKE_ARGS -G ${CMAKE_GENERATOR}
+  CONFIGURE_COMMAND ${CMAKE_COMMAND} -E env SIMPATH=${SIMPATH} FAIRROOTPATH=${FAIRROOTPATH}
+             ${CMAKE_COMMAND}
+             -G ${CMAKE_GENERATOR}
              -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
              -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
              -DCMAKE_C_FLAGS=${CMAKE_C_FLAGS}
@@ -44,6 +46,7 @@ ExternalProject_Add(NICAFEMTO
 	     -DJSROOT=${CMAKE_CURRENT_SOURCE_DIR}
              -DCMAKE_VERBOSE_MAKEFILE:BOOL=ON
              "${EXTRA_ARGS}"
+             ${CMAKE_CURRENT_SOURCE_DIR}/NicaFemto
   INSTALL_COMMAND  ${CMAKE_COMMAND} --build . --target install
 )