Fix include flags for c objects

Author: LKedward

src/fpm_backend.f90

@@ -242,7 +242,7 @@ subroutine build_target(model,target)
               // " -o " // target%output_file)
 
     case (FPM_TARGET_C_OBJECT)
-        call run(model%c_compiler//" -c " // target%source%file_name  &
+        call run(model%c_compiler//" -c " // target%source%file_name // target%compile_flags &
                 // " -o " // target%output_file)
 
     case (FPM_TARGET_EXECUTABLE)

src/fpm_targets.f90

@@ -445,7 +445,7 @@ subroutine resolve_target_linking(targets, model)
 
     integer :: i
     character(:), allocatable :: global_link_flags
-    character(:), allocatable :: global_compile_flags
+    character(:), allocatable :: global_include_flags
 
     if (size(targets) == 0) return
 
@@ -455,17 +455,16 @@ subroutine resolve_target_linking(targets, model)
         allocate(character(0) :: global_link_flags)
     end if
 
-    global_compile_flags = model%fortran_compile_flags
-
     if (allocated(model%link_libraries)) then
         if (size(model%link_libraries) > 0) then
             global_link_flags = global_link_flags // " -l" // string_cat(model%link_libraries," -l")
         end if
     end if
 
+    allocate(character(0) :: global_include_flags)
     if (allocated(model%include_dirs)) then
         if (size(model%include_dirs) > 0) then
-            global_compile_flags = global_compile_flags // &
+            global_include_flags = global_include_flags // &
             & " -I" // string_cat(model%include_dirs," -I")
         end if
     end if
@@ -474,7 +473,11 @@ subroutine resolve_target_linking(targets, model)
 
         associate(target => targets(i)%ptr)
 
-            target%compile_flags = global_compile_flags
+            if (target%target_type /= FPM_TARGET_C_OBJECT) then
+                target%compile_flags = model%fortran_compile_flags//" "//global_include_flags
+            else
+                target%compile_flags = global_include_flags
+            end if
 
             allocate(target%link_objects(0))