update so it can be built either standalone or as subdir with LAMMPS

tools/phonon/CMakeLists.txt

@@ -47,6 +47,10 @@ add_executable(phana
 )
 target_include_directories(phana PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}>)
 
+if(NOT LAMMPS_DIR)
+  set(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/../../cmake/Modules)
+  set(LAMMPS_THIRDPARTY_URL "https://download.lammps.org/thirdparty")
+endif()
 find_package(FFTW3)
 if(FFTW3_FOUND)
   target_compile_definitions(phana PRIVATE FFTW3)
@@ -56,12 +60,29 @@ endif()
 # build bundeled libraries
 add_subdirectory(tricubic)
 
+# standalone build must build our own version of linalg
+if(NOT LAMMPS_DIR)
+  if(NOT USE_INTERNAL_LINALG)
+    find_package(LAPACK)
+    find_package(BLAS)
+  endif()
+  if(NOT LAPACK_FOUND OR NOT BLAS_FOUND OR USE_INTERNAL_LINALG)
+    file(GLOB LINALG_SOURCES CONFIGURE_DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/../../lib/linalg/[^.]*.cpp)
+    add_library(linalg STATIC ${LINALG_SOURCES})
+    set(BLAS_LIBRARIES "$<TARGET_FILE:linalg>")
+    set(LAPACK_LIBRARIES "$<TARGET_FILE:linalg>")
+  else()
+    list(APPEND LAPACK_LIBRARIES ${BLAS_LIBRARIES})
+  endif()
+endif()
+
 option(USE_SPGLIB "Download and use spglib for phonon DOS and other optional properties" ON)
 if(USE_SPGLIB)
   set(SPGLIB_URL "https://github.com/spglib/spglib/archive/refs/tags/v1.11.2.1.tar.gz" CACHE STRING "URL for spglib v1.x tarball")
   set(SPGLIB_MD5 "3089782bc85b5034dd4765a18ee70bc7" CACHE STRING "MD5 checksum for spglib tarball")
   mark_as_advanced(SPGLIB_URL)
   mark_as_advanced(SPGLIB_MD5)
+  include(LAMMPSUtils)
   GetFallbackURL(SPGLIB_URL SPGLIB_FALLBACK)
 
   include(ExternalProject)

tools/phonon/version.h.in

@@ -0,0 +1 @@
+#define VERSION @CMAKE_PROJECT_VERSION@