build: include auto/config.h explicitly

Otherwise the symbols defined in config/config.h.in may not be defined,
depending on include-order.

src/nvim/assert.h

@@ -1,6 +1,8 @@
 #ifndef NVIM_ASSERT_H
 #define NVIM_ASSERT_H
 
+#include "auto/config.h"
+
 // support static asserts (aka compile-time asserts)
 
 // some compilers don't properly support short-circuiting apparently, giving
@@ -133,7 +135,7 @@
 ///
 /// @param MAX Maximum value of the narrowest type of operand.
 ///            Not used if compiler supports __builtin_add_overflow.
-#if HAVE_BUILTIN_ADD_OVERFLOW
+#ifdef HAVE_BUILTIN_ADD_OVERFLOW
 # define STRICT_ADD(a, b, c, t) \
   do { if (__builtin_add_overflow(a, b, c)) { abort(); } } while (0)
 #else
@@ -143,7 +145,7 @@
 
 /// @def STRICT_SUB
 /// @brief Subtracts (a - b) and stores result in `c`.  Aborts on overflow.
-#if HAVE_BUILTIN_ADD_OVERFLOW
+#ifdef HAVE_BUILTIN_ADD_OVERFLOW
 # define STRICT_SUB(a, b, c, t) \
   do { if (__builtin_sub_overflow(a, b, c)) { abort(); } } while (0)
 #else

src/nvim/log.c

@@ -12,6 +12,7 @@
 #endif
 #include <uv.h>
 
+#include "auto/config.h"
 #include "nvim/log.h"
 #include "nvim/types.h"
 #include "nvim/os/os.h"

src/nvim/log.h

@@ -4,6 +4,8 @@
 #include <stdio.h>
 #include <stdbool.h>
 
+#include "auto/config.h"
+
 #define DEBUG_LOG_LEVEL 0
 #define INFO_LOG_LEVEL 1
 #define WARN_LOG_LEVEL 2