gnu: swig: Fix build on i686.

* gnu/packages/patches/swig-guile-gc.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/swig.scm (swig)[source](patches): Use it.

gnu/local.mk

@@ -1154,6 +1154,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/soundtouch-CVE-2018-1000223.patch 	\
   %D%/packages/patches/steghide-fixes.patch			\
   %D%/packages/patches/superlu-dist-scotchmetis.patch		\
+  %D%/packages/patches/swig-guile-gc.patch			\
   %D%/packages/patches/swish-e-search.patch			\
   %D%/packages/patches/swish-e-format-security.patch		\
   %D%/packages/patches/synfigstudio-fix-ui-with-gtk3.patch 	\

gnu/packages/patches/swig-guile-gc.patch

@@ -0,0 +1,76 @@
+Fix garbage collection for Guile versions >= 2.0.12.  This issue showed
+up when running the tests on i686-linux.
+
+Taken from this upstream commit:
+https://github.com/swig/swig/commit/38f2ab0c30e369e63bbd0a6152108488d0de68e1
+
+diff --git a/Lib/guile/guile_scm_run.swg b/Lib/guile/guile_scm_run.swg
+index 274f197158..0d04cb7c62 100644
+--- a/Lib/guile/guile_scm_run.swg
++++ b/Lib/guile/guile_scm_run.swg
+@@ -99,6 +99,7 @@ SWIG_Guile_scm2newstr(SCM str, size_t *len) {
+ static int swig_initialized = 0;
+ static scm_t_bits swig_tag = 0;
+ static scm_t_bits swig_collectable_tag = 0;
++static scm_t_bits swig_finalized_tag = 0;
+ static scm_t_bits swig_destroyed_tag = 0;
+ static scm_t_bits swig_member_function_tag = 0;
+ static SCM swig_make_func = SCM_EOL;
+@@ -163,7 +164,19 @@ SWIG_Guile_PointerType(SCM object)
+   }
+   else scm_wrong_type_arg("SWIG-Guile-PointerType", 1, object);
+ }
+-  
++
++SWIGINTERN int
++SWIG_Guile_IsValidSmob(SCM smob)
++{
++  /* We do not accept smobs representing destroyed pointers, but we have to
++     allow finalized smobs because Guile >= 2.0.12 sets all smob instances
++     to the 'finalized' type before calling their 'free' function. This change
++     was introduced to Guile in commit 8dff3af087c6eaa83ae0d72aa8b22aef5c65d65d */
++  return SCM_SMOB_PREDICATE(swig_tag, smob)
++    || SCM_SMOB_PREDICATE(swig_collectable_tag, smob)
++    || SCM_SMOB_PREDICATE(swig_finalized_tag, smob);
++}
++
+ SWIGINTERN int
+ SWIG_Guile_ConvertPtr(SCM s, void **result, swig_type_info *type, int flags)
+ {
+@@ -179,8 +192,7 @@ SWIG_Guile_ConvertPtr(SCM s, void **result, swig_type_info *type, int flags)
+     *result = SCM_POINTER_VALUE(s);
+     return SWIG_OK;
+ #endif /* if SCM_MAJOR_VERSION >= 2 */
+-  } else if (SCM_SMOB_PREDICATE(swig_tag, smob) || SCM_SMOB_PREDICATE(swig_collectable_tag, smob)) {
+-    /* we do not accept smobs representing destroyed pointers */
++  } else if (SWIG_Guile_IsValidSmob(smob)) {
+     from = (swig_type_info *) SCM_CELL_WORD_2(smob);
+     if (!from) return SWIG_ERROR;
+     if (type) {
+@@ -239,7 +251,7 @@ SWIG_Guile_MarkPointerNoncollectable(SCM s)
+ {
+   SCM smob = SWIG_Guile_GetSmob(s);
+   if (!SCM_NULLP(smob)) {
+-    if (SCM_SMOB_PREDICATE(swig_tag, smob) || SCM_SMOB_PREDICATE(swig_collectable_tag, smob)) {
++    if (SWIG_Guile_IsValidSmob(smob)) {
+       SCM_SET_CELL_TYPE(smob, swig_tag);
+     }
+     else scm_wrong_type_arg(NULL, 0, s);
+@@ -252,7 +264,7 @@ SWIG_Guile_MarkPointerDestroyed(SCM s)
+ {
+   SCM smob = SWIG_Guile_GetSmob(s);
+   if (!SCM_NULLP(smob)) {
+-    if (SCM_SMOB_PREDICATE(swig_tag, smob) || SCM_SMOB_PREDICATE(swig_collectable_tag, smob)) {
++    if (SWIG_Guile_IsValidSmob(smob)) {
+       SCM_SET_CELL_TYPE(smob, swig_destroyed_tag);
+     }
+     else scm_wrong_type_arg(NULL, 0, s);
+@@ -419,6 +431,8 @@ SWIG_Guile_Init ()
+     scm_set_smob_print(swig_collectable_tag, print_collectable_swig);
+     scm_set_smob_equalp(swig_collectable_tag, equalp_swig);
+     scm_set_smob_free(swig_collectable_tag, free_swig);
++    /* For Guile >= 2.0.12. See libguile/smob.c:clear_smobnum */
++    swig_finalized_tag = swig_collectable_tag & ~0xff00;
+   }
+   if (ensure_smob_tag(swig_module, &swig_destroyed_tag,
+ 		      "destroyed-swig-pointer", "destroyed-swig-pointer-tag")) {

gnu/packages/swig.scm

@@ -22,6 +22,7 @@
   #:use-module (guix download)
   #:use-module (guix licenses)
   #:use-module (guix build-system gnu)
+  #:use-module (gnu packages)
   #:use-module (gnu packages pcre)
   #:use-module (gnu packages guile)
   #:use-module (gnu packages boost)
@@ -37,6 +38,7 @@
              (uri (string-append "mirror://sourceforge/" name "/" name "/"
                                  name "-" version "/"
                                  name "-" version ".tar.gz"))
+             (patches (search-patches "swig-guile-gc.patch"))
              (sha256
               (base32
                "0kf99ygrjs5616gsqhz1l7bib3a12izmxi7g48bwblbymr3z9ybw"))))