Patch darshan-apmpi.c to fix variable redefinition problem

* Make __darshan_disabled a local variable.
* Without this fix, the compile error messages shown below will appear.

  In file included from darshan-apmpi.c:18:
  darshan-apmpi.c: In function ‘__wrap_MPI_Barrier’:
  /home/runner/work/darshan/darshan/darshan-runtime/lib/darshan.h:227:9:
  error: redefinition of ‘__darshan_disabled’
    227 |     int __darshan_disabled =
  darshan_core_disabled_instrumentation()
        |         ^~~~~~~~~~~~~~~~~~
  darshan-apmpi.c:32:11: note: in expansion of macro ‘MAP_OR_FAIL’
     32 |           MAP_OR_FAIL(PMPI_Barrier);\
        |           ^~~~~~~~~~~
  darshan-apmpi.c:1389:5: note: in expansion of macro ‘TIME_SYNC’
   1389 |     TIME_SYNC(__real_PMPI_Barrier(comm));
        |     ^~~~~~~~~

Author: wkliao

Makefile.am

@@ -5,7 +5,7 @@
 
 ACLOCAL_AMFLAGS = -I maint/config
 
-SUBDIRS =
+SUBDIRS = modules .
 
 if BUILD_DARSHAN_RUNTIME
    SUBDIRS += darshan-runtime

configure.ac

@@ -57,7 +57,7 @@ fi
 dnl must configure subpackages even if they are not built
 AC_CONFIG_SUBDIRS([darshan-util])
 
-AC_CONFIG_FILES(Makefile)
+AC_CONFIG_FILES(Makefile modules/Makefile)
 
 AC_OUTPUT
 

modules/Makefile.am

@@ -0,0 +1,23 @@
+#
+# See COPYRIGHT notice in top-level directory.
+#
+# @configure_input@
+
+apmpi_c_src = $(srcdir)/autoperf/apmpi/lib/darshan-apmpi.c
+apmpi_c_saved = $(srcdir)/autoperf/apmpi/lib/saved_darshan-apmpi.c
+apmpi_c_patch = $(srcdir)/apmpi.patch
+
+# Rule to apply the patch
+$(apmpi_c_saved): $(apmpi_c_src) $(apmpi_c_patch)
+	cp -f $(apmpi_c_src) $(apmpi_c_saved)
+	patch -f -p0 $(apmpi_c_src) < $(apmpi_c_patch)
+	touch $@
+
+BUILT_SOURCES = $(apmpi_c_saved)
+
+EXTRA_DIST = apmpi.patch
+
+clean: $(apmpi_c_saved)
+	cp -f $(apmpi_c_saved) $(apmpi_c_src)
+	rm -f $(apmpi_c_saved) $(apmpi_c_src).*
+

modules/apmpi.patch

@@ -0,0 +1,27 @@
+--- darshan-apmpi.c.orig	2025-10-03 14:11:57.395296967 -0500
++++ darshan-apmpi.c	2025-10-03 14:22:12.684565527 -0500
+@@ -29,14 +29,16 @@
+ #define TIME_SYNC(FUNC) \
+           double tm1, tm2, tm3, tdiff, tsync;\
+           int ret; \
+-          MAP_OR_FAIL(PMPI_Barrier);\
+-          tm1 = APMPI_WTIME(); \
+-          ret = __real_PMPI_Barrier(comm); \
+-          tm2 = APMPI_WTIME(); \
+-          ret = FUNC; \
+-          tm3 = APMPI_WTIME(); \
+-          tdiff = tm3-tm2; \
+-          tsync = tm2-tm1
++          { \
++              MAP_OR_FAIL(PMPI_Barrier);\
++              tm1 = APMPI_WTIME(); \
++              ret = __real_PMPI_Barrier(comm); \
++              tm2 = APMPI_WTIME(); \
++              ret = FUNC; \
++              tm3 = APMPI_WTIME(); \
++              tdiff = tm3-tm2; \
++              tsync = tm2-tm1; \
++          }
+ #else
+ 
+ #define TIME_SYNC(FUNC) \