build: Allow using a system-provided SPIRV-Cross library.

Fixes: #17079

* Makefile.common [HAVE_BUILTINSPIRV_CROSS]: Include bundled
SPIRV-Cross sources only when using the builtin option, else...
[!HAVE_BUILTINSPIRV_CROSS]: Extend CXXFLAGS and LIBS.
* qb/config.libs.sh (BUILTINSPIRV_CROSS): Register new check_enabled
configure option, and add libraries/header checks.
* qb/config.params.sh (HAVE_BUILTINSPIRV_CROSS): Register new parameter.

Author: apteryks

Makefile.common

@@ -1895,6 +1895,7 @@ endif
 
 ifeq ($(HAVE_SPIRV_CROSS), 1)
    DEFINES += -DHAVE_SPIRV_CROSS
+ifeq ($(HAVE_BUILTINSPIRV_CROSS), 1)
    INCLUDE_DIRS += -I$(DEPS_DIR)/SPIRV-Cross
    OBJ += $(DEPS_DIR)/SPIRV-Cross/spirv_cross.o
    OBJ += $(DEPS_DIR)/SPIRV-Cross/spirv_cfg.o
@@ -1903,6 +1904,13 @@ ifeq ($(HAVE_SPIRV_CROSS), 1)
    OBJ += $(DEPS_DIR)/SPIRV-Cross/spirv_msl.o
    OBJ += $(DEPS_DIR)/SPIRV-Cross/spirv_parser.o
    OBJ += $(DEPS_DIR)/SPIRV-Cross/spirv_cross_parsed_ir.o
+else
+   CXXFLAGS += $(SPIRV_CROSS_CFLAGS)
+   LIBS += -lspirv-cross-core \
+           -lspirv-cross-glsl \
+           -lspirv-cross-reflect \
+           -lspirv-cross-msl
+endif
 endif
 
 ifeq ($(WANT_WGL), 1)

qb/config.libs.sh

@@ -662,6 +662,7 @@ check_enabled CXX GLSLANG glslang 'The C++ compiler is' false
 check_enabled CXX SPIRV_CROSS SPIRV-Cross 'The C++ compiler is' false
 
 check_enabled GLSLANG BUILTINGLSLANG 'builtin glslang' 'glslang is' true
+check_enabled SPIRV_CROSS BUILTINSPIRV_CROSS 'builtin spirv-cross' 'spirv-cross is' true
 
 if [ "$HAVE_GLSLANG" != no ]; then
    check_header cxx GLSLANG \
@@ -694,6 +695,27 @@ if [ "$HAVE_GLSLANG" != no ]; then
    fi
 fi
 
+if [ "$HAVE_SPIRV_CROSS" != no ]; then
+   check_lib cxx SPIRV_CROSS -lspirv-cross-core '' '' 'spirv_cross.hpp' 'spirv_cross'
+   check_lib cxx SPIRV_CROSS_GLSL -lspirv-cross-glsl
+   check_lib cxx SPIRV_CROSS_MSL -lspirv-cross-msl
+   check_lib cxx SPIRV_CROSS_REFLECT -lspirv-cross-reflect
+   if [ "$HAVE_SPIRV_CROSS" = no ] ||
+      [ "$HAVE_SPIRV_CROSS_GLSL" = no ] ||
+      [ "$HAVE_SPIRV_CROSS_MSL" = no ] ||
+      [ "$HAVE_SPIRV_CROSS_REFLECT" = no ]; then
+      if [ "$HAVE_BUILTINSPIRV_CROSS" != yes ]; then
+         die : "Notice: System spirv-cross libraries not found, \
+disabling spirv-cross support"
+         HAVE_SPIRV_CROSS=no
+      else
+         HAVE_SPIRV_CROSS=yes
+      fi
+   else
+      HAVE_SPIRV_CROSS=yes
+   fi
+fi
+
 if [ "$HAVE_CRTSWITCHRES" != no ]; then
    if [ "$HAVE_CXX11" = 'no' ]; then
       HAVE_CRTSWITCHRES=no

qb/config.params.sh

@@ -194,6 +194,7 @@ C89_GLSLANG=no
 HAVE_BUILTINGLSLANG=auto   # Bake in glslang support
 C89_BUILTINGLSLANG=no
 HAVE_SPIRV_CROSS=auto      # SPIRV-Cross support (requires C++11)
+HAVE_BUILTINSPIRV_CROSS=auto    # Use bundled SPIRV-Cross source
 C89_SPIRV_CROSS=no
 HAVE_METAL=no              # Metal support (macOS-only)
 C89_METAL=no