fix: Fix enable/disable-profiling flag (#1018)

The variable enable_profiling exists just because AC_ARG_ENABLE([profiling] is defined.
If it is redefined in the exist condition, the both enable and disable flags will enable the profiling,
just if the flag is missing it will be disabled.
Reference in Warning here: https://autotools.io/autoconf/arguments.html
diff --git a/configure b/configure
index eff3888..82ec447 100755
--- a/configure
+++ b/configure
@@ -12947,9 +12947,7 @@
 # Check if enable profiling
 # Check whether --enable-profiling was given.
 if test "${enable_profiling+set}" = set; then :
-  enableval=$enable_profiling; enable_profiling=yes
-else
-  :
+  enableval=$enable_profiling;
 fi
 
  if test x$enable_profiling = xyes; then
diff --git a/configure.ac b/configure.ac
index 8778a03..b2656e7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -58,9 +58,7 @@
 
 # Check if enable profiling
 AC_ARG_ENABLE([profiling],
-    AS_HELP_STRING([--enable-profiling], [Enable iperf3 profiling binary]),
-    [enable_profiling=yes],
-    [:])
+    AS_HELP_STRING([--enable-profiling], [Enable iperf3 profiling binary]))
 AM_CONDITIONAL([ENABLE_PROFILING], [test x$enable_profiling = xyes])
 
 # Checks for header files.