Include from build dir first

This fixes out of tree builds by ensuring that configure artifacts are included
from the build dir.

Before, out of tree builds would preferably include files from the src dir, as
the include path was defined as follows (ignoring includes from ext/ and sapi/) :

    -I$(top_builddir)/main
    -I$(top_srcdir)
    -I$(top_builddir)/TSRM
    -I$(top_builddir)/Zend
    -I$(top_srcdir)/main
    -I$(top_srcdir)/Zend
    -I$(top_srcdir)/TSRM
    -I$(top_builddir)/

As a result, an out of tree build would include configure artifacts such as
`main/php_config.h` from the src dir.

After this change, the include path is defined as follows:

    -I$(top_builddir)/main
    -I$(top_builddir)
    -I$(top_srcdir)/main
    -I$(top_srcdir)
    -I$(top_builddir)/TSRM
    -I$(top_builddir)/Zend
    -I$(top_srcdir)/Zend
    -I$(top_srcdir)/TSRM

Author: arnaud-lb

build/Makefile.global

@@ -2,8 +2,7 @@ mkinstalldirs = $(top_srcdir)/build/shtool mkdir -p
 INSTALL = $(top_srcdir)/build/shtool install -c
 INSTALL_DATA = $(INSTALL) -m 644
 
-DEFS = -I$(top_builddir)/main -I$(top_srcdir)
-COMMON_FLAGS = $(DEFS) $(INCLUDES) $(EXTRA_INCLUDES) $(CPPFLAGS) $(PHP_FRAMEWORKPATH)
+COMMON_FLAGS = $(CORE_INCLUDES) $(INCLUDES) $(EXTRA_INCLUDES) $(CPPFLAGS) $(PHP_FRAMEWORKPATH)
 
 all: $(all_targets)
 	@echo

configure.ac

@@ -1349,12 +1349,14 @@ LIBZEND_BASIC_CHECKS
 LIBZEND_DLSYM_CHECK
 LIBZEND_OTHER_CHECKS
 
+CORE_INCLUDES="$CORE_INCLUDES -I\$(top_builddir)/main -I\$(top_builddir)"
 INCLUDES="$INCLUDES -I\$(top_builddir)/TSRM"
 INCLUDES="$INCLUDES -I\$(top_builddir)/Zend"
 
 if test "$abs_srcdir" != "$abs_builddir"; then
-  INCLUDES="$INCLUDES -I\$(top_srcdir)/main -I\$(top_srcdir)/Zend"
-  INCLUDES="$INCLUDES -I\$(top_srcdir)/TSRM -I\$(top_builddir)/"
+  CORE_INCLUDES="$CORE_INCLUDES -I\$(top_srcdir)/main -I\$(top_srcdir)"
+  INCLUDES="$INCLUDES -I\$(top_srcdir)/Zend"
+  INCLUDES="$INCLUDES -I\$(top_srcdir)/TSRM"
 fi
 
 ZEND_EXTRA_LIBS="$LIBS"
@@ -1540,6 +1542,7 @@ PHP_SUBST_OLD(EXTRA_LDFLAGS)
 PHP_SUBST_OLD(EXTRA_LDFLAGS_PROGRAM)
 PHP_SUBST_OLD(EXTRA_LIBS)
 PHP_SUBST_OLD(ZEND_EXTRA_LIBS)
+PHP_SUBST_OLD(CORE_INCLUDES)
 PHP_SUBST_OLD(INCLUDES)
 PHP_SUBST_OLD(EXTRA_INCLUDES)
 PHP_SUBST_OLD(INSTALL_IT)