build system: remove --disable-protoc option

for some reason, "make distcheck" fails when the build is configured
with --disable-protoc. i haven't been able to track down the root cause
(it appears the build is trying to generate the generated pb-c files for
the test cases, but the test cases should be disabled when
--disable-protoc is specified). so, remove the --disable-protoc option.
libprotobuf-c should always be tested as part of a build, and this can't
be done unless protoc-c is built. this also reduces the number of build
combinations that need to be tested.

Makefile.am

@@ -86,8 +86,6 @@ endif
 # protoc-c
 #
 
-if BUILD_PROTOC_C
-
 bin_PROGRAMS += protoc-c/protoc-c
 protoc_c_protoc_c_SOURCES = \
 	protoc-c/c_bytes_field.cc \
@@ -124,14 +122,10 @@ protoc_c_protoc_c_LDADD = \
 	$(protobuf_LIBS) \
 	-lprotoc
 
-endif
-
 #
 # protobuf-c tests
 #
 
-if BUILD_PROTOC_C
-
 check_PROGRAMS += \
 	t/generated-code/test-generated-code \
 	t/generated-code2/test-generated-code2
@@ -188,13 +182,10 @@ EXTRA_DIST += \
 	t/test-full.proto \
 	t/generated-code2/common-test-arrays.h
 
-endif
-
 #
 # protobuf-c-rpc tests
 #
 
-if BUILD_PROTOC_C
 if BUILD_RPC
 
 check_PROGRAMS += \
@@ -211,7 +202,6 @@ protobuf_c_rpc_t_test_rpc_LDADD = \
 	protobuf-c-rpc/libprotobuf-c-rpc.la
 
 endif
-endif
 
 #
 #

configure.ac

@@ -24,8 +24,6 @@ AC_CHECK_HEADERS(sys/uio.h)
 AC_CHECK_HEADERS(unistd.h)
 AC_CHECK_HEADERS(winsock.h)
 
-AC_PATH_PROG(PROTOC, protoc)
-
 PKG_PROG_PKG_CONFIG
 if test -n "$PKG_CONFIG"; then
     # Horrible hack for systems where the pkg-config install directory is simply wrong!
@@ -38,18 +36,9 @@ else
     AC_MSG_ERROR([pkg-config is required!])
 fi
 
-AC_ARG_ENABLE(
-    [protoc],
-    AS_HELP_STRING([--disable-protoc], [Disable building the protobuf-c compiler])
-)
-AS_IF(
-    [test "x$enable_protoc" != "xno"],
-    [
-        PKG_CHECK_MODULES([protobuf], [protobuf])
-        AC_LANG_PUSH([C++])
-    ]
-)
-AM_CONDITIONAL([BUILD_PROTOC_C], [test "x$enable_protoc" != "xno"])
+PKG_CHECK_MODULES([protobuf], [protobuf])
+AC_LANG_PUSH([C++])
+AC_PATH_PROG(PROTOC, protoc)
 
 AC_ARG_ENABLE(
     [rpc],