Remove Eigen3 from arpack.pc

Eigen3 is only needed for arpackSolver.hpp, which is independent from
the library.  If desired, a separate pkg-config file should be created
for the solver itself, which should contain something like:

    Requires: arpack, eigen3 >= 3.3

Also remove Eigen3 from arpack-ng-config.cmake since it serves the same
purpose.

CMakeLists.txt

@@ -740,7 +740,6 @@ set(PACKAGE_VERSION ${arpack_ng_VERSION})
 set(PACKAGE_URL "https://github.com/opencollab/arpack-ng/")
 set(LAPACK_LIBS "${LAPACK_LIBRARIES}")
 set(BLAS_LIBS "${BLAS_LIBRARIES}")
-set(EIGEN3_CFLAGS "-I${EIGEN3_INCLUDE_DIR}")
 configure_file(arpack.pc.in arpack${LIBSUFFIX}.pc @ONLY)
 install(FILES ${CMAKE_CURRENT_BINARY_DIR}/arpack${LIBSUFFIX}.pc
         DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig)

arpack-ng-config.cmake.in

@@ -13,7 +13,7 @@
 #   target_link_libraries(main PARPACK::PARPACK)
 
 # Create local variables.
-set(arpack_ng_INCLUDE_DIRS "@CMAKE_INSTALL_FULL_INCLUDEDIR@/arpack;@EIGEN3_INCLUDE_DIR@;${MPI_Fortran_INCLUDE_DIRS};${MPI_C_INCLUDE_DIRS};${MPI_CXX_INCLUDE_DIRS}")
+set(arpack_ng_INCLUDE_DIRS "@CMAKE_INSTALL_FULL_INCLUDEDIR@/arpack;${MPI_Fortran_INCLUDE_DIRS};${MPI_C_INCLUDE_DIRS};${MPI_CXX_INCLUDE_DIRS}")
 if(EXISTS "@CMAKE_INSTALL_FULL_LIBDIR@/libarpack.a")
   set(arpack_ng_LIBRARIES "@CMAKE_INSTALL_FULL_LIBDIR@/libarpack.a;@LAPACK_LIBRARIES@;@BLAS_LIBRARIES@")
 elseif(EXISTS "@CMAKE_INSTALL_FULL_LIBDIR@/libarpack.so")

arpack.pc.in

@@ -8,4 +8,4 @@ Description: Collection of Fortran77 subroutines designed to solve large scale e
 Version: @PACKAGE_VERSION@
 URL: @PACKAGE_URL@
 Libs: -L${libdir} -larpack@LIBSUFFIX@ @LAPACK_LIBS@ @BLAS_LIBS@
-Cflags: -I${includedir}/arpack @EIGEN3_CFLAGS@
+Cflags: -I${includedir}/arpack

configure.ac

@@ -12,7 +12,6 @@ AC_PROG_FC
 AC_PROG_CC
 AC_PROG_CXX
 PKG_PROG_PKG_CONFIG
-AC_PROG_SED
 
 dnl Check for BLAS libraries
 AX_BLAS([], [AC_MSG_ERROR([cannot find BLAS libraries])])
@@ -261,7 +260,6 @@ AC_SUBST([CMAKE_INSTALL_FULL_LIBDIR], ["$libdir"])  # FIXME: need to recursively
 AC_SUBST([CMAKE_INSTALL_FULL_INCLUDEDIR], ["$includedir"])
 AC_SUBST([BLAS_LIBRARIES], ["$BLAS_LIBS"])  # FIXME: need a filename, not a -l flag
 AC_SUBST([LAPACK_LIBRARIES], ["$LAPACK_LIBS"])
-AC_SUBST([EIGEN3_INCLUDE_DIR], [`echo "$EIGEN3_CFLAGS" | sed -e s/-I//`])
 AC_CONFIG_FILES([arpack-ng-config.cmake])
 
 AC_SUBST([arpack_ng_VERSION], ["$VERSION"])