gallium: Fix automake for Android (v2)

Chromium OS uses Autotools and pkg-config when building Mesa for
Android. The gallium drivers were failing to find the headers and
libraries for zlib and Android's libbacktrace.

v2:
  - Don't add a check for zlib.pc. configure.ac already checks for
    zlib.pc elsewhere. [for tfiga]
  - Check for backtrace.pc separately from the other Android libs.
    [for tfiga]

Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>

configure.ac

@@ -1836,6 +1836,9 @@ for plat in $platforms; do
 
     android)
         PKG_CHECK_MODULES([ANDROID], [cutils hardware sync])
+        if test -n "$with_gallium_drivers"; then
+            PKG_CHECK_MODULES([BACKTRACE], [backtrace])
+        fi
         DEFINES="$DEFINES -DHAVE_ANDROID_PLATFORM"
         ;;
 

src/gallium/Automake.inc

@@ -59,6 +59,12 @@ GALLIUM_COMMON_LIB_DEPS += \
 	$(LIBDRM_LIBS)
 endif
 
+if HAVE_PLATFORM_ANDROID
+GALLIUM_COMMON_LIB_DEPS += \
+	$(ANDROID_LIBS) \
+	$(BACKTRACE_LIBS)
+endif
+
 GALLIUM_WINSYS_CFLAGS = \
 	-I$(top_srcdir)/src \
 	-I$(top_srcdir)/include \

src/gallium/auxiliary/Makefile.am

@@ -21,6 +21,10 @@ libgallium_la_SOURCES = \
 	$(NIR_SOURCES) \
 	$(GENERATED_SOURCES)
 
+if HAVE_PLATFORM_ANDROID
+libgallium_la_SOURCES += util/u_debug_stack_android.cpp
+endif
+
 if HAVE_LIBDRM
 
 AM_CFLAGS += \