Turn off IPC support when sys/shm.h is missing, to fix compilation on Termux.

configure.ac

@@ -173,6 +173,7 @@ yes
 
 if test "$IPC_SUPPORT" = "yes"; then
   AC_CHECK_HEADERS([sys/ipc.h], [], [IPC_SUPPORT=no])
+  AC_CHECK_HEADERS([sys/shm.h], [], [IPC_SUPPORT=no])
   AC_CHECK_HEADERS([sys/param.h])
   if test "$IPC_SUPPORT" = "yes"; then
     AC_CHECK_FUNCS([shmget], [], [IPC_SUPPORT=no])

docs/NEWS.md

@@ -1,3 +1,7 @@
+### UNRELEASED
+
+ * *fix:* turn off IPC support if _sys/shm.h_ is not available, for compilation on Termux
+
 ### 1.9.25 - 22 December 2024
 
  * *fix:* test failure of **--watchfd** on macOS corrected ([#124](https://codeberg.org/a-j-wood/pv/issues/124))

src/include/config.h.in

@@ -194,6 +194,9 @@
 /* Define to 1 if you have the <sys/param.h> header file. */
 #undef HAVE_SYS_PARAM_H
 
+/* Define to 1 if you have the <sys/shm.h> header file. */
+#undef HAVE_SYS_SHM_H
+
 /* Define to 1 if you have the <sys/stat.h> header file. */
 #undef HAVE_SYS_STAT_H