Include the library directory for the sake of 3rdparty

When compiling library files under `3rdparty/`, the directory containing
the `.c` file that is being compiled is not the current directory, so
headers from the `library/` directory are not found. Fix this by
adding `.` to the include path.

This was not detected until now because as of this commit, no 3rdparty
source file requires a header under `library/`.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/scripts/generate_visualc_files.pl b/scripts/generate_visualc_files.pl
index 8bf8de9..a3a2925 100755
--- a/scripts/generate_visualc_files.pl
+++ b/scripts/generate_visualc_files.pl
@@ -64,6 +64,15 @@
 );
 my $include_directories = join(';', map {"../../$_"} @include_directories);
 
+# Directories to add to the include path when building the library, but not
+# when building tests or applications.
+my @library_include_directories = qw(
+    library
+);
+my $library_include_directories =
+  join(';', map {"../../$_"} (@library_include_directories,
+                              @include_directories));
+
 my @excluded_files = qw(
     3rdparty/everest/library/Hacl_Curve25519.c
 );
@@ -202,7 +211,7 @@
     my $out = slurp_file( $main_tpl );
     $out =~ s/SOURCE_ENTRIES\r\n/$source_entries/m;
     $out =~ s/HEADER_ENTRIES\r\n/$header_entries/m;
-    $out =~ s/INCLUDE_DIRECTORIES\r\n/$include_directories/g;
+    $out =~ s/INCLUDE_DIRECTORIES\r\n/$library_include_directories/g;
 
     content_to_file( $out, $main_out );
 }