THRIFT-3285 c_glib: Library: Use AM_CPPFLAGS for include paths, not AM_CFLAGS
This follows the description of the two variables in the automake
documentation.
diff --git a/lib/c_glib/Makefile.am b/lib/c_glib/Makefile.am
index 4e0aa88..67ebf20 100755
--- a/lib/c_glib/Makefile.am
+++ b/lib/c_glib/Makefile.am
@@ -24,7 +24,7 @@
lib_LTLIBRARIES = libthrift_c_glib.la
pkgconfig_DATA = thrift_c_glib.pc
-AM_CFLAGS = -Isrc -I src/thrift/c_glib
+AM_CPPFLAGS = -Isrc -I src/thrift/c_glib
# Define the source files for the module