build: qcom-soc plugin by default disabled

It will not be automatically enabled by the implicit
--enable-all-plugins; instead, it must be explicitly enabled with
--enable-plugin-qcom-soc.

This plugin only makes sense under very specific SoC builds, so there
is no point in always building it by default. It should be explicitly
requested only in those SoC builds that are really going to make use
of it (e.g. postmarketOS).

configure.ac

@@ -490,7 +490,7 @@ MM_ENABLE_PLUGIN([option],
 MM_ENABLE_PLUGIN([option-hso],
                  [with_shared_option])
 MM_ENABLE_PLUGIN([pantech])
-MM_ENABLE_PLUGIN([qcom-soc])
+MM_ENABLE_PLUGIN_DISABLED([qcom-soc])
 MM_ENABLE_PLUGIN([quectel])
 MM_ENABLE_PLUGIN([samsung],
                  [with_shared_icera])

m4/mm-enable-plugin.m4

@@ -20,18 +20,18 @@ AC_ARG_ENABLE(all-plugins,
 ])
 
 dnl Usage:
-dnl  MM_ENABLE_PLUGIN([NAME],[WITH_SHARED_NAME_1,WITH_SHARED_NAME_2,...])
-AC_DEFUN([MM_ENABLE_PLUGIN],
+dnl  MM_ENABLE_PLUGIN_FULL([NAME],[DEFAULT],[WITH_SHARED_NAME_1,WITH_SHARED_NAME_2,...])
+AC_DEFUN([MM_ENABLE_PLUGIN_FULL],
 [dnl
 m4_pushdef([var_enable_plugin], patsubst([enable_plugin_$1], -, _))dnl
 m4_pushdef([VAR_ENABLE_PLUGIN], patsubst(translit([enable_plugin_$1], [a-z], [A-Z]), -, _))dnl
 AC_ARG_ENABLE(plugin-$1,
               AS_HELP_STRING([--enable-plugin-$1], [Build $1 plugin]),
               [],
-              [var_enable_plugin=$enable_all_plugins])
+              [var_enable_plugin=$2])
 if test "x$var_enable_plugin" = "xyes"; then
   AC_DEFINE([VAR_ENABLE_PLUGIN], 1, [Define if $1 plugin is enabled])
-m4_ifval([$2],[m4_foreach(with_shared,[$2],[dnl
+m4_ifval([$3],[m4_foreach(with_shared,[$3],[dnl
   with_shared="yes"
 ])])dnl
 fi
@@ -40,6 +40,20 @@ m4_popdef([VAR_ENABLE_PLUGIN])dnl
 m4_popdef([var_enable_plugin])dnl
 ])
 
+dnl Usage:
+dnl  MM_ENABLE_PLUGIN([NAME],[WITH_SHARED_NAME_1,WITH_SHARED_NAME_2,...])
+AC_DEFUN([MM_ENABLE_PLUGIN],
+[dnl
+MM_ENABLE_PLUGIN_FULL($1,$enable_all_plugins,$2)
+])
+
+dnl Usage:
+dnl  MM_ENABLE_PLUGIN_DISABLED([NAME],[WITH_SHARED_NAME_1,WITH_SHARED_NAME_2,...])
+AC_DEFUN([MM_ENABLE_PLUGIN_DISABLED],
+[dnl
+MM_ENABLE_PLUGIN_FULL($1,"no",$2)
+])
+
 dnl Usage:
 dnl  MM_BUILD_SHARED([NAME])
 AC_DEFUN([MM_BUILD_SHARED],