Don't mix up C and C++ compilers
Part of https://gitlab.com/tiagobar/ripperx/-/merge_requests/3

diff --git a/configure.ac b/configure.ac
index b9dd913..942ebc2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3,15 +3,13 @@
 
 AC_PREREQ([2.65])
 AC_INIT([ripperX], [3.0.1], [thothix@protonmail.com])
-AC_CONFIG_SRCDIR([src/main.c])
+AC_CONFIG_SRCDIR([src/main.cpp])
 AC_CONFIG_AUX_DIR([config])
 AM_INIT_AUTOMAKE([foreign])
 AC_CONFIG_HEADERS([config.h])
-${CFLAGS=""}
-${CXXFLAGS=""}
 
 # Checks for programs.
-AC_PROG_CC([g++])
+AC_PROG_CC
 AC_PROG_CXX
 
 PKG_PROG_PKG_CONFIG